Download 3. Structure Of DB2

Table Of Contents
1.
PURPOSE AND SCOPE OF THE DOCUMENT .................................................. 1
1.1.
1.2.
2.
USERS OF THE DOCUMENT ................................................................................... 1
ASSOCIATED DOCUMENTS ................................................................................... 1
INTRODUCTION ..................................................................................................... 2
2.1.
DATABASE MANAGEMENT SYSTEMS (DBMS) .................................................... 3
2.2.
TYPES OF DBMS ................................................................................................ 4
2.2.1.
Relational DBMS ...................................................................................... 4
2.2.2.
HIERARCHICAL DBMS ........................................................................... 6
2.2.3.
Net Work DBMS ........................................................................................ 7
2.3.
SAMPLE DB2 DATABASE ..................................................................................... 8
3.
STRUCTURE OF DB2 .............................................................................................. 9
3.1.
HIERARCHY OF DATA STRUCTURES .................................................................... 9
3.2.
DATABASES ......................................................................................................... 9
3.3.
DB2 STORAGE GROUPS ....................................................................................... 9
3.4.
TABLE SPACES..................................................................................................... 9
3.4.1.
Simple Tablespace..................................................................................... 9
3.4.2.
Segmented Table Space ............................................................................. 9
3.4.3.
Partitioned Table Space ............................................................................ 9
3.5.
TABLES ................................................................................................................ 9
3.6.
INDEX SPACES ..................................................................................................... 9
3.7.
INDEXES .............................................................................................................. 9
3.8.
VIEWS.................................................................................................................. 9
3.9.
SYNONYMS .......................................................................................................... 9
3.10.
ALIASES............................................................................................................... 9
3.11.
DB2 CATALOG .................................................................................................... 9
3.12.
DB2 DIRECTORY ................................................................................................. 9
3.13.
ACTIVE AND ARCHIVE LOGS ............................................................................... 9
3.14.
BUFFER POOLS .................................................................................................... 9
4.
DATA TYPES .......................................................................................................... 39
4.1.
NUMERIC DATA ................................................................................................. 39
4.1.1.
Nulls ........................................................................................................ 39
4.2.
STRING DATA .................................................................................................... 39
4.3.
CHARACTER FORMAT ........................................................................................ 39
4.4.
DATE/TIME DATA .............................................................................................. 39
4.5.
EQUIVALENT COBOL DECLARATIONS OF DATA TYPES...................................... 39
5.
SQL PROGRAMMING .......................................................................................... 49
5.1.
DDL STATEMENTS ............................................................................................ 51
5.1.1.
Create Database...................................................................................... 51
5.1.2.
Create Table Space ................................................................................. 51
5.1.3.
Create Table ............................................................................................ 51
5.1.4.
Create View ............................................................................................. 51
5.1.5.
Create Index ............................................................................................ 51
5.1.6.
Alter Table............................................................................................... 51
5.1.7.
Drop ........................................................................................................ 51
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DB2 Fundamentals
5.2.
DML STATEMENTS............................................................................................ 64
5.2.1.
Select ....................................................................................................... 64
5.2.2.
Joining Tables ......................................................................................... 64
5.2.3.
Sub Queries ............................................................................................. 64
5.2.4.
Union ....................................................................................................... 64
5.2.5.
Insert ....................................................................................................... 64
5.2.6.
Update ..................................................................................................... 64
5.2.7.
Delete ...................................................................................................... 64
5.3.
CONTROL STATEMENTS ..................................................................................... 82
5.3.1.
Grant ....................................................................................................... 82
5.3.2.
Revoke ..................................................................................................... 82
5.3.3.
Commit .................................................................................................... 82
5.3.4.
Roll Back ................................................................................................. 82
6.
PROGRAM STRUCTURE ..................................................................................... 87
6.1.
HOST VARIABLES .............................................................................................. 87
6.1.1.
Declaring Host Variables ....................................................................... 87
6.2.
INDICATOR VARIABLES...................................................................................... 87
6.3.
SQLCA ............................................................................................................. 87
6.4.
COBOL STRUCTURE OF SQLCA ........................................................................ 87
6.5.
SQLCA RETURN CODES ................................................................................... 87
6.6.
SQLCA WARNINGS .......................................................................................... 87
6.7.
IMPORTANT SQL CODES .................................................................................... 87
6.8.
STATIC SQL ...................................................................................................... 87
6.9.
DYNAMIC SQL .................................................................................................. 87
6.10.
EXAMPLE FOR A DB2 APPLICATION PROGRAM ................................................ 87
7.
PROGRAM PREPARATION .............................................................................. 122
7.1.
STEPS IN PROGRAM PREPARATION .................................................................. 122
7.2.
DCLGEN (DECLARATIONS GENERATOR ) ........................................................ 122
7.3.
PRECOMPILE .................................................................................................... 122
7.4.
BIND ................................................................................................................ 122
7.4.1.
Binding A DBRM To A Package ........................................................... 122
7.4.2.
Binding An Application Plan ................................................................ 122
7.5.
COMPILE AND LINKEDIT .................................................................................. 122
7.6.
OVERVIEW OF DB2 APPLICATION PROGRAM PREPARATION AND EXECUTION 122
7.7.
ASSOCIATING LOAD MODULES AND PACKAGES.............................................. 122
8.
SECURITY FEATURES ...................................................................................... 140
8.1.
PRIVILEGES ...................................................................................................... 140
8.2.
REFERENTIAL INTEGRITY ................................................................................. 140
8.2.1.
DB2 Enforcement Of Referential Integrity ........................................... 140
8.2.2.
Referential Integrity Enforcement Rules ............................................... 140
8.2.3.
Example For Referential Integrity Violation ........................................ 140
8.3.
DATABASE RECOVERY IN CASE OF FAILURE................................................... 140
8.3.1.
Unit Of Recovery ................................................................................... 140
8.3.2.
Data Recovery ....................................................................................... 140
9.
CONCURRENCY .................................................................................................. 157
9.1.
9.2.
CONCURRENCY................................................................................................ 157
LOCKING STRATEGY ........................................................................................ 157
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DB2 Fundamentals
9.3.
9.4.
9.5.
10.
10.1.
10.2.
11.
11.1.
11.2.
11.3.
12.
LOCK SIZES AND TYPES .................................................................................. 157
ACQUIRE RELEASE PARAMETERS .................................................................... 157
ISOLATION PARAMETER ................................................................................... 157
DB2I (DB2 INTERACTIVE ) .......................................................................... 167
DB2I ............................................................................................................... 167
SPUFI ............................................................................................................. 167
UTILITIES ........................................................................................................ 171
LOAD ............................................................................................................... 171
RUNSTATS ....................................................................................................... 171
REORG ............................................................................................................. 171
ADVANCED DB2 ............................................................................................. 179
12.1.
MORE ABOUT INDEXES ................................................................................... 179
12.1.1.
Example Of An Index ............................................................................ 179
12.1.2.
Clustered Indexes .................................................................................. 179
12.1.3.
Non Clustered Indexes .......................................................................... 179
12.2.
SPECIAL REGISTERS ......................................................................................... 179
12.3.
MORE ABOUT LOCKS ...................................................................................... 179
12.3.1.
Modes Of Table And Tablespace Locks ................................................ 179
12.3.2.
Modes Of Row And Page Locking ........................................................ 179
12.3.3.
Lock Mode Compatibility Of Table And Table Space Locks ................ 179
12.3.4.
Lockmode Compatibility Of Row And Page Locks ............................... 179
12.4.
INVOKING ONLINE UTILITIES ........................................................................... 179
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DB2 Fundamentals
1.
Purpose and Scope of the Document
The Purpose of this document is to train fresh Software Engineers who would like
to get familiarised with DB2 and as a reference material for application
programmers.
1.1.
Users of the Document
This document is intended for database designers, database application
programmers, students and teachers and more generally anyone who wishes to
broaden his or her knowledge of the database, DB2.
1.2. Associated Documents
No associated documents
2.
Introduction
DB2 ( IBM DATABASE2 ) is a highly successful relational database management
system. DB2 enables it’s users to create, update and control relational database
using STRUCTURED QUERY LANGUAGE (SQL). Designed to meet the needs
of small and large business alike, DB2 is available on a number of platforms. we
will be dealing with DB2 on MVS.
RISC SYSTEM/6000
DB2 FOR
OS/2
DB2 FOR
AIX
DB2 FOR
HP-UX
DB2 FOR
SOLARIS
DB2 FOR
WINDOWS /NT
DB2 FOR
SINIX
DB2 FOR
MVS
DB2 FOR
VSE & VM
DB2 FOR
OS/400
2.1.
Database Management Systems (DBMS)
DATABASE MANAGEMENT SYSTEMS deal with the problem of storing and
retrieving large amounts of data. DBMS provides an environment to share data
among it’s users. Preserving the correctness of data and restoring the database
in failure are major concerns for DBMS.
DBMS
DATABASE
APPLICATION
QUERY
PROGRAM
PROCESSOR
STORAGE MANAGER
DATA
 DBMS CONSIST OF DATA, HARDWARE, SOFTWARE AND USERS
 BENEFITS OF DBMS ARE
 REDUCE REDUNDANCY
 AVOID INCONSISTENCY
 SHARE DATA
 MANIPULATES DATA EFFICIENTLY
 FAULT TOLERANT
 DATA INDEPENDENCE
2.2.
Types Of DBMS
Depending on data models used, database management systems are mainly
divided into three.
 RELATIONAL DBMS
 HIERARCHICAL DBMS
 NETWORK DBMS
2.2.1. Relational DBMS
DB2 is based on relational data model which was formulated by DR. E.F CODD in
1970. Relational systems have their origin in the mathematical theory of relations.
Using relational data model , IBM developed DB2 in 1983.
A RELATIONAL SYSTEM IS A SYSTEM IN WHICH
 THE DATA IS PERCEIVED BY THE USER AS TABLES
 QUERIES ARE USED TO EXTRACT DATA FROM THE DATABASE.
 ALL DATA VALUES ARE ATOMIC. ie EVERY ROW AND COLUMN
POSITION CONTAINS ONLY ONE DATA VALUE; NEVER A LIST OF
VALUES
 EXAMPLE OF RELATIONAL DBMS IS DB2
SAMPLE DATABASE FOR COMPARING DIFFERENT DBMS
TABLE S
S#
TABLE SP
SNAME
S1
S2
S3
SMITH
JONES
BLAKE
STATUS
20
10
30
CITY
LONDON
PARIS
PARIS
TABLE P
P#
PNAME
COLOR
P1
P2
P3
P4
NUT
BOLT
SCREW
SCREW
RED
GREEN
BLUE
RED
WEIGHT
12
17
17
14
CITY
LONDON
PARIS
ROME
LONDON
S#
P#
QTY
S1
S1
S1
S2
S2
S3
P1
P2
P3
P1
P2
P2
300
200
400
300
400
200
 TABLE S represents SUPPLIERS. Each supplier has a unique SUPPLIER
NUMBER (S#), a SUPPLIER NAME (SNAME), a RATING (STATUS) and a
LOCATION OF THE SUPPLIER (CITY).
 TABLE P represents PARTS. Each kind of part has a unique PART NUMBER
(P#), a PART NAME (PNAME), a COLOUR (COLOR), a WEIGHT (WEIGHT)
and a location where the PART IS STORED (CITY).
 TABLE SP represents SHIPMENTS. It connects other two tables. It
REPRESENTS a shipment of parts of kind P1 by the supplier called S1 and
the shipment quantity.
 In a relational data model TABLES are called RELATIONS, ROWS are called
TUPLES and COLUMNS are referred as ATTRIBUTES.
 In a relational data mode association of ROWS of different TABLES are done
using COLUMN VALUES of common columns.
 DB2 relates TABLE S and SP using the COLUMN SUPPLIER NUMBER(S#).
TABLE P and SP are related using the COMMON attribute PART NUMBER
(P#). TABLES S and P are related using COLUMN (CITY)
2.2.2. HIERARCHICAL DBMS
Hierarchical View Of Supplier And Parts Database
In hierarchical database suppliers, parts and shipments are different databases
SUPPLIERS DATABASE
PARTS DATABASE
S1
P1
…..
S2
SMITH
NUT
JONES
20
RED
12
LONDON
10
LONDON
SHIPMENTS DATABASE
PARIS
SHIPMENT
SEGMENT
LCHILD
 In this view data is represented by a simple TREE STRUCTURES and DBMS
links these data bases using pointers.
 The user sees three individual trees for supplier database, each tree has a
parent supplier. Each tree can be called a supplier record occurrence.
Similarly you can see part record occurrence and shipment record occurrence.
 Shipment database contains the shipment quantity. The logical child of
shipment database consists of supplier number , part number and pointers to
corresponding databases .Similarly the supplier and parts databases also
contains logical child which points to the shipment database. Now the user can
access shipment from supplier and part databases. Similarly parts and
supplier databases are also accessed from shipment database
 IMS (Information management system) is an example of Hierarchical DBMS
2.2.3. Net Work DBMS
SUPPLIER
RECORD SET
PART RECORD
SET
S1 SMITH…..
P1 NUT …..
S2 JONES…..
P2 BOLT…….
QUANTITY RECORDS
300
400
…….
 NETWORK DBMS consists of owner databases and member databases. The
member database can be accessed only via the owner database.
 In the example there are two owners for a member database. Supplier and
part record sets are owners of shipment record set. Using this database the
user can access the shipment of a particular part by a specific supplier
 The supplier S1 supplies part P1 of quantity 300. From the supplier S1 there is
a pointer towards the supplied quantity and another pointer connects this to
the corresponding part. An owner can have more than one pointer towards
different quantities.
 Example of network database is IDMS(Integrated database management
system)
2.3.
Sample Db2 Database
The sample database consists of THREE tables and these tables are used
through out this book.
TABLE S
TABLE SP
S#
SNAME
S1
S2
S3
S4
S5
SMITH
JONES
BLAKE
CLARK
ADAMS
STATUS
20
10
30
20
30
CITY
LONDON
PARIS
PARIS
LONDON
ATHENS
TABLE P
P#
PNAME
P1
P2
P3
P4
P5
P6
NUT
BOLT
SCREW
SCREW
CAM
COG
COLOR
RED
GREEN
BLUE
RED
BLUE
RED
WEIGHT
12
17
17
14
12
19
CITY
S#
P#
QTY
S1
S1
S1
S1
S1
S1
S2
S2
S3
S4
S4
S4
P1
P2
P3
P4
P5
P6
P1
P2
P2
P2
P4
P5
300
200
400
200
100
100
300
400
200
200
300
400
LONDON
PARIS
ROME
LONDON
PARIS
LONDON
 TABLE S represents SUPPLIERS. Each SUPPLIER has a unique SUPPLIER
NUMBER (S#), a SUPPLIER NAME (SNAME), a RATING (STATUS) and a
location of the SUPPLIER (CITY). PRIMARY KEY IS S#.
 TABLE P represents PARTS. Each kind of part has a unique PART NUMBER
(P#), a PART NAME (PNAME), a COLOUR (COLOR), a WEIGHT (WEIGHT)
and a LOCATION where the PART IS STORED (CITY).
PRIMARY KEY IS P#
 TABLE SP represents SHIPMENTS .It connects other TWO TABLES .It
represents a SHIPMENT of PARTS OF KIND P1 by the SUPPLIER called S1
and the SHIPMENT QUANTITY. For a given SHIPMENT the combination of
S# and P# is unique .That is the PRIMARY KEY is the COMBINATION of the
above mentioned and the FOREIGN KEYS ARE S# AND P#
3.
Structure Of DB2
This chapter deals with the definitions and examples of objects present in
DB2.The topics included in this chapter are
3.1.
Hierarchy Of Data Structures
3.2.
Databases
3.3.
DB2 Storage Groups
3.4.
Table Spaces
3.4.1. Simple Tablespace
3.4.2. Segmented Table Space
3.4.3. Partitioned Table Space
3.5.
Tables
3.6.
Index Spaces
3.7.
Indexes
3.8.
Views
3.9.
Synonyms
3.10. Aliases
3.11. DB2 Catalog
3.12. DB2 Directory
3.13. Active And Archive Logs
3.14. Buffer Pools
STRUCTURE OF DB2
THE ELEMENTS OF DB2 ARE DIVIDED INTO
TWO BROAD CATEGORIES
DATA STRUCTURES
SYSTEM STRUCTURES
 DATA STRUCTURES CONTAIN USER DATA AND ARE ACCESSED
UNDER USER’S DIRECTION.
 SYSTEM STRUCTURES ARE CONTROLLED AND ACCESSED BY DB2
 DATA STRUCTURES CONSIST OF
 DATABASES
 DB2 STORAGE GROUPS
 TABLE SPACES
 TABLES
 INDEX SPACES
 INDEXES
 VIEWS
 SYNONYMS
 ALIASES
 SYSTEM STRUCTURES MAINLY CONSIST OF




DB2 CATALOG
DB2 DIRECTORY
ACTIVE AND ARCHIVE LOGS
BUFFER POOLS
HIERARCHY OF DATA STRUCTURES
DATABASE D1
STORAGE
GROUP G1
TABLE SPACE S1
TABLE T1
TABLE T2
VOLUME 1
(DASD)
INDEX X1
VOLUME 2
(DASD)
INDEX X2
PARTITIONED
TABLESPACE
S2
TABLE T3
PART 1
TABLE T3
PART 2
STORAGE
GROUP G2
VOLUME2
(3380)
PARTITIONED INDEX X3
PART 1
PARTITIONED INDEX X3
PART 2
Hierarchy Of Data structures
 The total collection of stored data is divided into a number of disjoint
databases. They are USER DATABASES and SYSTEM DATABASES.
 Each database is divided into a number of disjoint ‘spaces’, that is several
TABLESPACES and INDEX SPACES. A space is a dynamically extendible
collection of PAGES, where PAGE is a block of physical storage.
 Each table space contains one or more stored tables. A stored table contains
a set of stored records. A given stored table must be wholly contained within a
single table space.
 Each INDEXSPACE contains exactly one index. A given index must be wholly
contained with in a single index space. A given stored table and all of its
associated indexes must be wholly contained within a single DATABASE.
 Each space (TABLE SPACE or INDEX SPACE) has an associated STORAGE
GROUP. When a space needs to be extended, storage is acquired from
appropriate storage group.
DATA BASES
DATABASE1
TABLESPACE1
INDEX 1
TABLE 1
TABLE 2
INDEX 2
TABLESPACE 2
 DATABASE IS A COLLECTION OF A NUMBER OF TABLE SPACES ALONG
WITH A SET OF INDEX SPACES
 A STORED TABLE AND ALL OF IT’S ASSOCIATED INDEXES MUST BE IN
A SINGLE DATABASE
 WHEN YOU CREATE A TABLESPACE OR TABLE AND DO NOT SPECIFY
THE DATABASE THE OBJECT WILL BE CREATED IN THE DEFAULT
DATABASE DSNDB04
DB2 STORAGE GROUPS
STORAGE GROUP 1
VOLUME 1
VOLUME 2
 USER AND SYSTEM DATABASES ARE PHYSICALLY STORED IN THE
DATASETS OF SPECIFIED STORAGE GROUPS
 STORAGE GROUP IS A SET OF VOLUMES OF DIRECT ACCESS
STORAGE DEVICES(DASD).
 PARTS OF SINGLE DATABASE CAN BE STORED IN DIFFERENT
STORAGE GROUPS
 DEFAULT STORAGE GROUP IS SYSDEFLT
TABLE SPACES
TABLESPACE 1
TABLE 1
TABLE 2
SIMPLE
SEGMENTED
PARTITIONED
 TABLESPACE IS MADE UP OF ONE OR MORE VSAM LINEAR DATASETS
(LDS ), WHERE ONE OR MORE TABLES ARE STORED.
 A TABLE SPACE IS DIVIDED INTO 4K OR 32K PAGES.
 A PAGE IS A UNIT OF I/O TRANSMISSION.
 A PAGE MAY CONTAIN ONE OR MORE ROWS (MAX 127).
 A ROW MUST LIE WITHIN A PAGE.
Table Spaces
A TABLE SPACE can be thought of as a logical address space on secondary
storage that is to hold one or more stored tables. Table spaces are divided into
equal sized units called PAGES which are written or read from DASD. Tables are
physically stored in one or more VASM linear datasets.
A table space can consists of 1 to 64 VSAM datasets which can together contain
up to 64 GIGABYTES of data. When you create a table space you can specify
the database and storage group to which the tablespace belongs and table space
type. As the amount of data in tables grow storage will be acquired from
appropriate storage groups and added to the tablespace.
Fundamentally the table space is a storage unit for recovery and reorganization. If
the table space is very large the RECOVERY and REORGANIZATION could take
a long time. Hence making the tablespace simple, segmented, or partitioned can
drastically affect the performance.
SIMPLE TABLESPACE
SIMPLE TABLESPACE
FREE
PAGE
FREE
SPACE
4K
PAGE
RECORD OF TABLE 1
RECORD OF TABLE 2
 SIMPLE TABLESPACE CONTAINS ONE OR MORE TABLES
 RECORDS OF DIFFERENT TABLES ARE STORED IN AN INTERLEAVED
MANNER.
 IMPROVE ACCESS TIME FOR LOGICALLY RELATED DATA
Simple Tablespace
In simple table space records of tables are interleaved .Records of different tables
may be present in a single page and to find all rows of a table a scan of the whole
table space is needed. But by loading the data in an appropriately interleaved
manner; accessing logically related data will be more efficient.
If a table is dropped, its rows are not deleted. The space occupied by the rows
does not become available until the table space is reorganized. All tables in a
simple table space must reside in the same user-defined data set or in the same
storage group.
one stored table per table space is always the most satisfactory arrangement in
the case of simple TABLE SPACE.
SEGMENTED TABLESPACE
SEGMENT1
SEGMENT2
4K
PAGE
SEGMENT3
TABLE SPACE HAVING A SEGMENT SIZE 4
RECORD OF TABLE 1
RECORD OF TABLE 2
 TABLE SPACE IS DIVIDED INTO A NUMBER OF SEGMENTS.
 RECORDS OF DIFFERENT STORED TABLES ARE NOT INTERLEAVED IN
A SINGLE SEGMENT.
 A SEGMENTED TABLE SPACE CAN CONTAIN ONE OR MORE TABLES.
 SEQUENTIAL ACCESS TO A PARTICULAR TABLE IS MORE EFFICIENT.
Segmented Tablespace
In a SEGMENTED TABLESPACE the tablespace is divided into segments and
each segment consists of a logically contiguous set of N PAGES. N must be a
multiple of 4 in the range 4 TO 64 and is same for all segments in the table
space. The size of the segment is specified while creating the tablespace.
Each segment in the segmented tablespace contains rows from only one table.
But the tablespace can contain multiple tables, in different SEGMENTS. In order
to find a row, it is not necessary to scan the entire table space, but only the
segments that contain the table. Hence sequential access to a particular table is
more efficient.
If a table in a segmented table space is dropped, the space for that table can be
reused without performing a reorganization of the table space.
A segmented table space can have between 1 AND 32 VSAM linear data sets.
the maximum size of a data set in the segmented table space is 2 GIGABYTES
and so, the maximum size of a segmented table space is 64 GIGABYTES .
PARTITIONED TABLESPACE
A—F
PARTITION1
G—P
PARTITION2
Q—Z
PARTITION3
RECORD OF TABLE 1
 A PARTITIONED TABLESPACE CAN CONTAIN ONLY ONE TABLE.
 EACH PARTITION CONTAINS A PART OF ONE TABLE.
 THE PARTITIONS CAN BE INDEPENDENTLY ASSIGNED TO DIFFERENT
STORAGE GROUPS.
 IMPROVED DATA AVAILABILITY AND QUERY RESPONSE TIME.
Partitioned Tablespace
PARTITIONED TABLESPACES are intended for stored tables that are sufficiently
large. Partitioned table contains exactly one stored table, partitioned in
accordance with value ranges of a particular column or column combination .
A partition can be 1, 2, OR 4 GIGABYTES in length, depending on the number of
partitions contained in the entire table space. If only one partition is defined on the
table space, then its MAXIMUM SIZE IS 4 GIGABYTES.
Partitioning a table space provides several advantages for large tables. When
DB2 scans data to answer a query it can scan through partitions simultaneously
instead of scanning through the entire table from the beginning to end.
A utility can work on all partitions simultaneously instead of working on one
partition at a time. Also, different utilities can work on different partitions
simultaneously. This can significantly reduce the amount of time needed for a
utility to finish.
TABLES
TABLE S
KEY
ROWS
COLUMNS
S#
SNAME
STATUS
S1
S2
S3
S4
S5
SMITH
JONES
BLAKE
CLARK
ADAMS
20
10
30
20
30
CITY
LONDON
PARIS
PARIS
LONDON
ATHENS
 A RELATIONAL DATABASE STORES DATA IN THE FORM OF TABLES.
 TABLE CONSISTS OF A NUMBER OF RECORDS.
 RECORD CONTAINS COLUMNS, ROWS, KEYS etc.
 EACH RECORD SHOULD BE CONTAINED IN A SINGLE PAGE BUT A
TABLE CAN BE SPREAD OVER PAGES.
VIEWS
BASE TABLE AS IT EXISTS
STORAGE
VIEW AS THE PROGRAM’S
LOGIC SEES IT.
TABLE S
VIEW
S# SNAME STATUS CITY
S#
STATUS
CITY
 A VIEW CAN INCLUDE ALL OR SOME OF THE COLUMNS FROM ONE OR
MORE BASE TABLES
 VIEWS ARE CREATED FOR BASE TABLES
COMBINATION OF VIEWS AND TABLES.
OR VIEWS
OR A
 VIEWS ARE LOGICAL REPRESENTATION OF DATA THAT EXISTS IN
BASE TABLES.
 VIEWS ARE USED FOR SIMPLICITY AND SECURITY.
Views
A VIEW is a named table that is represented, not by its own physically separate,
distinguishable stored data, but rather by its definition in terms of other named
tables. VIEWS are created for base tables or views or a combination of views and
tables.
When you define a view DB2 stores the definition of the view in the DB2 catalog.
Data is physically present in base tables only and not in views. When a view is
accessed then data is dynamically retrieved from the base table.
Advantages Of Views
1. They provide a certain amount of logical data independence in restructuring
the database
2. They allow the same data to be seen by different users in different ways.
3. Automatic security is provided for data that is present in the base table by
creating a view in which sensitive data is not visible.
INDEX SPACES
INDEX SPACE 1
INDEX 1
 ONLY ONE INDEX IS STORED IN AN INDEX SPACE
 INDEX SPACE IS AUTOMATICALLY CREATED WHEN THE
CORRESPONDING INDEX IS CREATED.
 PAGES IN AN INDEX SPACE ARE 4K BYTES IN SIZE.
 INDEX SPACE FOR PARTITIONED TABLESPACE ARE PARTITIONED.
INDEX
INDEX 1
RID
VALUE
PAGE P
T
 INDEX CONSISTS OF TWO PARTS ,RECORD ID (RID) AND INDEXED
VALUE.
 A TABLE CAN HAVE ANY NUMBER OF ASSOCIATED INDEXES.
 INDEXES ARE USED TO IMPROVE PERFORMANCE AND IN SOME
CASES TO ENSURE UNIQUENESS.
 IN THE EXAMPLE INDEX IS USED TO FIND A RECORD (T) IN PAGE P.
 DB2 DETERMINES WHETHER TO USE AN INDEX OR NOT
Indexes
An index contains values from one or more of a table’s columns and a pointer to
the record in a data which matches the index value. DB2 will find data more
efficiently by scanning the index and following the pointer than by scanning the
entire tablespace.
Record ID of index has two parts. First part is to identify the page where the
record lies and the second part is the byte offset from the bottom of the page
identifying the record. Index is structured in ascending or descending sequence
on one or more columns. A given value of interest can be located quickly in the
index because of their ascending or descending structure.
An index created on a table in a partitioned table space is a partitioned index and
is divided into multiple index spaces.
Indexes are of two types, unique and non unique indexes. A non unique index
can reference duplicate values, a UNIQUE INDEX will not. You can create an
index any time after you create the table. But creating an index before loading the
data provides significant performance advantages.
Indexes can be clustered or non clustered. A clustering index is one in which the
records are physically stored in data pages in the sequential order of their index
values. The index is used to control physical placement of the indexed records.
Newly inserted records are physically stored such that the physical sequence of
those records in storage closely approximates the logical sequence as defined by
the index. In a non clustered index the records will not be in the order of index
values.
A table can have any number of indexes but it can have only one clustered index.
Clustering is extremely important for optimization purpose. The optimizer will try to
choose an access path based on the clustering index .
For detailed explanation of indexes please refer ‘More about indexes’, chapter
12.
ALIASES
 AN ALIAS IS AN ALTERNATIVE NAME FOR A TABLE OR VIEW. IT IS A
QUALIFIED NAME THAT CAN BE USED BY ANY AUTHORIZATION ID.
 AN ALIAS CAN BE DEFINED FOR A TABLE OR VIEW THAT WAS
CREATED BY SOME OTHER USER AND FOR WHICH YOU WOULD
OTHERWISE HAVE TO USE A FULLY QUALIFIED NAME
 ALIASES WERE DESIGNED FOR A DISTRIBUTED ENVIRONMENT TO
AVOID HAVING TO REFERENCE THE LOCATION QUALIFIER OF TABLE
OR VIEW
 ALIAS IS NOT PRIVATE TO THE CREATOR
 AN ALIAS CAN BE DEFINED ON AN UNDEFINED NAME. THAT IS THE
OBJECT ON WHICH THE ALIAS IS CREATED NEED NOT BE PRESENT
AT THE CREATION TIME
Aliases
Aliases are useful for creating meaningful names for TABLES and VIEWS.
ALIASES are created using CREATE ALIAS statement. One user can use an
ALIAS created by another user since aliases are not private to the creator
EXAMPLE
Suppose user ALPHA creates a table called SAMPLE.
CREATE TABLE SAMPLE
The fully qualified name of the table SAMPLE is ALPHA.SAMPLE and another
user BETA can refer to the table sample by its fully qualified name.
SELECT *
FROM ALPHA.SAMPLE
The user BETA can create an alias called ZTEST for the table ALPHA.SAMPLE
using create statement.
CREATE ALIAS ZTEST FOR ALPHA.SAMPLE
And now he can refer to the table SMPLE created by ALPHA by simply referring
to the alias ZTEST
SELECT *
FROM ZTEST
Another user GAMMA can also use BETA’S ALIAS ZTEST to refer to ALPHA’S
SAMPLE table.
SELECT * FROM
BETA.ZTEST
SYNONYMS
 SYNONYMS ARE USEFUL FOR CREATING MORE MEANINGFUL NAME
FOR A PERSON USING A TABLE OR VIEW
 A SYNONYM IS AN UNQUALIFIED NAME THAT CAN ONLY BE USED BY
THE AUTHORIZATION ID THAT CREATED IT.
 A SYNONYM IS PRIVATE TO THE USER WHO CREATES IT
 SYNONYM CANNOT REFER TO REMOTE TABLE IN A DISTRIBUTED
DATA ENVIRONMENT
 A SYNONYM CAN ONLY BE DEFINED ON THE NAME OF AN EXISTING
TABLE OR VIEW.
Synonyms
A SYNONYM like an ALIAS is an alternative name for a table. Creating a
SYNONYM for a table or view will allow the creator to refer to those tables and
views by the more meaningful synonym created by him.
EXAMPLE
Suppose user ALPHA creates a table called SAMPLE.
CREATE TABLE SAMPLE
The fully qualified name of the table SAMPLE is ALPHA.SAMPLE and another
user BETA can refer to the table sample by its fully qualified name.
SELECT *
FROM ALPHA.SAMPLE
The user BETA can create a SYNONYM called ZTEST for the table
ALPHA.SAMPLE using create statement.
CREATE SYNONYM ZTEST FOR ALPHA.SAMPLE
And now he can refer to the table SAMPLE created by ALPHA by simply referring
to the SYNONYM ZTEST
SELECT *
FROM ZTEST
However the user BETA and table ALPHA.SAMPLE must be at the same site.
Also the name ZTEST is completely private to the user BETA. Another user
GAMMA cannot use the synonym created by BETA and if it wants a synonym it
should be created on ALPHA.SAMPLE.
DB2 CATALOG
DB2
CATALOG CONSISTS OF TABLES WHICH
CONTAIN
INFORMATION ABOUT OBJECTS DEFINED UNDER
DB2
4
SYSTEM .
CATALOG
WHEN A
TABLES
ARE
THE
NEW TABLE IS CREATED
UPDATED .
THEY
ARE
SYSIBM.SYSTABLES ,
SYSIBM.SYSCOLUMNS .
SYSIBM.SYSTABLESPACE ,
SYSIBM.SYSTABAUTH
 EXAMPLES OF CATALOG TABLES
 SYSIBM.SYSTABLES
CONTAINS INFORMATION OF A TABLE. WHEN A NEW TABLE
IS CREATED DB2 INSERTS ONE ROW INTO THIS CATALOG
TABLE.
 SYSIBM.SYSCOLUMNS
CONTAINS INFORMATION ABOUT THE COLUMNS IN A TABLE.
THIS TABLE CONTAINS ONE ROW FOR EVERY COLUMN OF
EACH ROW IN A TABLE .
 SYSIBM.SYSTABLESPACE
CONTAINS INFORMATION OF THE TABLE SPACE CREATED.
THIS TABLE CONTAINS ONE ROW FOR EACH TABLESPACE.
 SYSIBM.SYSTABAUTH
CONTAINS INFORMATION OF THE TABLE NAMES AND
AUTHORIZATION ID’s WHICH HAVE PRIVILEGES ON THAT
TABLE
DB2 Catalog
The CATALOG in DB2 is a system database that contains information concerning
various objects that are of interest to DB2 itself. Examples of such objects are
tables, views, indexes, databases, plans, packages, access privileges, and so on.
These information is essential, if the system is to able to do it’s job properly.
CATALOG itself contains TABLES and you can see the contents of catalog tables
using normal query language ( SQL ). When you create, drop or alter any
structure, DB2 updates or deletes rows of the catalog that describe the structure.
DBA ‘s and application programmers may use catalog tables to determine
 Which application plan and packages use which indexes
 Which tablespaces, tables and indexes are in a database
 An index’s structure, whether unique or clustered or the number of levels
present in an index
 The amount of physical space used and remaining
 Who created an object and who owns it.
 Which plans and packages use objects in a database.
 Who has authorization to create objects
 Which plans and packages use which tables and tables and views
 Which synonyms and aliases have been created on tables and views
 Who is authorized to execute which plans and packages etc
Optimizer component of bind will use catalog information to choose best access
strategy.
DB2 DIRECTORY
DB2
DIRECTORY
REQUIRED
CONTAINS INFORMATION
TO START DB2
AND DB2
USES
THE DIRECTORY DURING NORMAL OPERATION.
DB2
DIRECTORY CONSISTS OF A SET OF DB2
TABLES STORED IN 5 TABLE SPACES IN SYSTEM
DATABASE DSNDB01.
 SKELETON CURSOR TABLESPACE (SCT02) CONTAINS PLANS
 SKELETON PACKAGE TABLE (SPT01) CONTAINS PACKAGES
 LOG RANGE TABLE SPACE (SYSLGRNX) CONTAINS THE RBA
(RELATIVE BYTE ADDRESS ) THE LOG DATASET
 SYSTEM UTILITIES TABLE SPACE (SYSUTILX)
INFORMATION ABOUT RUNNING UTILITIES
CONTAINS THE
 THE DATABASE DESCRIPTOR TABLE SPACE (DBD01) CONTAINS
INTERNAL CONTROL BLOCKS THAT DESCRIBE THE DATABASES
EXISTING WITHIN DB2.
 CANNOT ACCESS DIRECTORY USING SQL
ACTIVE AND ARCHIVE LOGS
DB2 RECORDS ALL DATA CHANGES AND SIGNIFICANT
EVENTS IN A LOG AS THEY OCCUR
DB2 WRITES EACH LOG RECORD TO A DASD DATA SET
CALLED THE ACTIVE LOG.
WHEN THE ACTIVE LOG IS FULL, DB2 COPIES THE CONTENTS
OF THE ACTIVE LOG TO A DASD CALLED THE ARCHIVE LOG
 IN THE CASE OF FAILURE DB2 USES LOGS TO RECOVER DATA.
 THE ARCHIVE LOG CAN CONSIST OF UP TO 1000 DATA SETS EACH OF
WHICH IS A SEQUENTIAL DATA SET.
BUFFER POOLS
BUFFER POOLS ARE AREAS OF VIRTUAL
STORAGE THAT TEMPORARILY STORE PAGES
OF TABLE SPACES OR INDEXES.
THE DATA REMAINS IN THE BUFFER UNTIL
DB2 DECIDES TO USE THE SPACE FOR
ANOTHER PAGE
 BUFFER POOLS HOLD THE MOST FREQUENTLY ACCESSED DATA.
 USING BUFFER POOLS IMPROVE PERFORMANCE.
 DB2 ALLOWS TO USE 50 BUFFER POOLS THAT CONTAIN 4KB
BUFFERS AND 10 BUFFER POOLS THAT CONTAIN 32KB BUFFERS.
 4KB BUFFER POOLS ARE BP0 TO BP49
 32KB BUFFER POOLS ARE BP32K TO BP32K9
Buffer Pools
Buffer pools, also known as virtual buffer pools, are areas of virtual storage used
temporarily to store pages of table spaces or indexes. When an application
program needs to access a row of a table, DB2 retrieves the page containing that
row and places the page in a buffer. If the row is changed, the buffer must be
written back to the table space. If the needed data is already in a buffer, the
application program will not have to wait for it to be retrieved from DASD. The
result is faster performance.
DB2 can provide 2 types of buffer pools, 4K and 32K buffer pools. There are fifty
4K buffer pools named BP0, BP1, P49 and ten 32K buffer pools named BP32K,
BP32K1, BP32K9. DB2 manages each buffer pools separately . Generally system
administrator decides how much memory to allocate for buffer pools. The more
memory allocated to buffer pool the more data it can hold and therefore the
greater the likelihood that an application request will find the data there.
4.
Data Types
This chapter describes various data types used in DB2 and their examples.
COBOL declarations of the corresponding DATA TYPES are also included.
The sub divisions of this chapter are
4.1.
Numeric Data
4.1.1. Nulls
4.2.
String Data
4.3.
Character Format
4.4.
Date/Time Data
4.5.
Equivalent Cobol Declarations Of Data Types
DATA TYPES
EVERY COLUMN IN A TABLE IS ASSIGNED A SPECIFIC
TYPE AND SIZE OF DATA
CATEGORIES OF DATA TYPES
NUMERIC DATA
STRING DATA
DATE / TIME DATA
 EACH COLUMN IN A TABLE MUST BE DEFINED
 COLUMN DEFINITION MUST INCLUDE THE DATA TYPE AND SIZE
 ALL DATA TYPES CAN INCLUDE NULL VALUES.
NUMERIC DATA
SMALLINT :
TWO BYTE BINARY INTEGER , 15 BITS AND SIGN.
INTEGER
FOUR BYTE BINARY INTEGER, 31 BITS AND SIGN.
:
DECIMAL (P,Q):
PACKED DECIMAL NUMBER HAVING P DIGITS OF
WHICH Q DIGITS ARE AFTER THE ASSUMED DECIMAL
POINT
FLOAT (M)
REAL
IF M IS BETWEEN 1 AND 21 THEN IT IS SINGLE
PRECISION FLOATING POINT AND IT OCCUPIES FOUR
BYTES. IT CAN ALSO BE REFERRED AS REAL
FLOAT (M)
FLOAT
IF M IS BETWEEN 22 AND 53 THEN IT IS SINGLE
PRECISION FLOATING POINT AND IT OCCUPIES EIGHT
BYTES. IT CAN ALSO BE REFERRED AS FLOAT
RANGE OF VALUES
SMALLINT
-32768 to +32767
INTEGER
-2147483648 to +2147483647
DECIMAL (P ,Q)
MAXIMUM 31 DIGITS
0 < P < 32 AND ( 0 <= Q <= P )
REAL
FLOAT
5.4E-79 to 7.2E+75.
5.4E-79 to 7.2E+75.
EXAMPLES OF NUMERIC DATA DECLARATION
SPKZ
DRU
HDNR
DECIMAL(5, 2)
SMALLINT
INTEGER
NULLS
 SQL SYSTEMS LIKE DB2 REPRESENT MISSING INFORMATION IN A
COLUMN BY MEANS OF SPECIAL MARKERS CALLED NULLS.
 THE PRESENCE OF NULL VALUE IN A COLUMN DEPENDS ON THE
COLUMN DEFINITION .
 THREE OPTIONS, SPECIFIED IN COLUMN DEFINITION WHICH DEAL
WITH NULL VALUES ARE
 NOT NULL
 NULL
 NOT NULL WITH DEFAULT
 IF A COLUMN IS DECLARED AS NOT NULL THEN DB2 WILL NOT
ALLOW NULL VALUES ON THAT COLUMN
 WHEN A COLUMN IS DECLARED AS NULL WHICH IS THE DEFAULT,
DB2 WILL ALLOW NULL VALUE ON THAT COLUMN

NOT NULL WITH DEFAULT MEANS THAT THE COLUMN IN
QUESTION CANNOT CONTAIN NULLS, BUT IT IS STILL LEGAL TO OMIT
A VALUE FOR THE COLUMN
EXAMPLES
SPKZ
DRU
HDNR
DECIMAL(5, 2)
SMALLINT
INTEGER
NULL
NOT NULL
NOT NULL WITH DEFAULT
Nulls
Null values are used in a table when actual values are unknown. Suppose the
weight of a part in the SUPPLIER-PARTS DATABASE is null, then it means that
(1) The part exists
(2) It does have a weight
(3) We do not know what the value is
In other words we do not know a genuine weight value that can sensibly be put in
the weight slot in the row for the part in question. Instead we mark that slot as null
and we interpret that mark to mean precisely that we do not know what the real
value is. we can insert a null value in the WEIGHT column if it is declared as
NULL. But if it is declared as NOT NULL WITH DEFAULT, it is possible to insert a
row into the table without specifying a value for WEIGHT column. In that case the
column will contain default values corresponding to the column data type.
Suppose that NOT NULL is specified for column WEIGHT in the SUPPLIERPARTS DATABASE, then this will guarantee that every row in table P will always
contain a genuine (not null) WEIGHT value. In other words a value must always
be provided for column WEIGHT when a row is inserted into the P table.
If a given column is allowed to contain nulls and a row inserted into the table with
no value provided for that column DB2 will automatically place a null in that
position. Suppose that the WEIGHT column in supplier-table database is
specified as NULL, then we can insert a row in the table P without specifying a
value for WEIGHT. DB2 will automatically put a null value in that column.
NOT NULL WITH DEFAULT means the column in question cannot contain nulls
but it is nevertheless still legal to omit a value for the column on insert. If a row is
inserted and no value is provided for some column to which NOT NULL WITH
DEFAULT applies DB2 automatically places one of the following non null default
values in that position.




Zero for numeric items
Blanks for fixed length string columns
Empty (zero length string) for varying length string columns
The value of CURRENT DATE or CURRENT TIME or CURRENT
TIMESTAMP for variables declared with attributes DATE, TIME or
TIMESTAMP.
STRING DATA
CHARACTER FORMAT
CHARACTER(n) : FIXED LENGTH STRING OF n 8 BIT CHARACTERS
OCCUPYING N BYTES
VARCHAR(n) :
VARYING LENGTH STRING UP TO n 8 BIT CHARACTERS
OCCUPYING n+2 BYTES . FIRST TWO BYTES ARE
USED FOR STORING THE LENGTH OF THE VARIABLE
LONG VARCHAR : VARYING LENGTH CHARACTER STRING WHOSE
MAXIMUM LENGTH WILL BE DECIDED BY DB2
RANGE OF VALUES
CHARACTER(n)
:
1 TO 254
VARCHAR(n)
:
MUST BE LESS THAN PAGE SIZE (4K)
LONG VARCHAR
:
MAXIMUM LENGTH IS DETERMINED BY
THE AMOUNT OF SPACE AVAILABLE IN
A PAGE
EXAMPLES OF CHARACTER DATA REPRESENTATION
SPKZ
NUM
VAR
CHAR (20)
VARCHAR (60)
LONG VARCHAR
GRAPHIC FORMAT
GRAPHIC(n) :
FIXED LENGTH STRING OF N 16 BIT CHARACTERS
OCCUPYING 2n BYTES
VARGRAPHIC(n) : VARYING LENGTH STRING UP TO N 16 BIT
CHARACTERS OCCUPYING 2n+2 BYTES . FIRST TWO
BYTES ARE USED FOR STORING THE LENGTH OF THE
VARIABLE
LONG VARGRAPHIC :
VARYING LENGTH 16 BIT CHARACTER STRING
WHOSE MAXIMUM SIZE WILL BE DECIDED BY
DB2
RANGE OF VALUES
GRAPHIC(N) :
1 TO 127
VARGRAPHIC(N) :
N MUST BE LESS THAN HALF THE PAGE SIZE
(2K)
LONG VARGRAPHIC:
MAXIMUM LENGTH IS DETERMINED BY THE
AMOUNT OF SPACE AVAILABLE IN A PAGE
EXAMPLES OF GRAPHIC DATA DECLARATIONS
TABKOST
TABID
TEMP
GRAPHIC (10)
VARGRAPHIC (80)
LONG VARRRAPHIC
DATE / TIME DATA
INTERNAL REPRESENTATIONS
DATE
YYYYMMDD
TIME
HHMMSS
TIMESTAMP
YYYYMMDDHHMMSSNNNNNN
 DATE IS REPRESENTED AS A SEQUENCE OF EIGHT UNSIGNED
PACKED DECIMAL DIGITS OCCUPYING 4 BYTES
 TIME IS REPRESENTED AS A SEQUENCE OF SIX UNSIGNED PACKED
DECIMAL DIGITS OCCUPYING 3 BYTES
 TIMESTAMP IS REPRESENTED AS A SEQUENCE OF 20 UNSIGNED
PACKED DECIMAL DIGITS OCCUPYING 10 BYTES
EXAMPLES OF DATE TIME DECLARATIONS
CCTEMP
CCDAT
CCSTAMP
DATE
TIME
TIMESTAMP
Date / Time Data
Columns whose data types are DATE, TIME, OR TIMESTAMP are represented in
an internal form that is transparent to the user of SQL. But DATES, TIMES, AND
TIMESTAMPS can also be represented by DATE/TIME strings. These are
character string representations of date values. When you retrieve date/time
values they must be assigned to properly declared character string variables.
When a date or time is assigned to a variable, the string format is determined by
a precompiler option or subsystem parameter. When a string representation of a
datetime value is used in other operations, it is converted to a datetime value.
However, this can be done only if the string representation is compatible with the
date / time value
Example
The ISO date format ‘1987-10-12’ is internally stored in 4 bytes. But you must
assign a variable with 10 bytes as host variable for retrieving the above date.
EQUIVALENT COBOL DECLARATIONS OF DATA TYPES
DATATYPE
COBOL DECLARATION
CCTEMP SMALLINT
01 CCTEMP PIC S9(4) COMP.
CCTEMP INT
CCTEMP DECIMAL(9,3)
01 CCTEMP PIC S9(9) COMP.
01 CCTEMP PIC S9(6)V9(3) COMP-3.
CCTEMP FLOAT(21)
01 CCTEMP COMP-1.
CCTEMP FLOAT(53)
01 CCTEMP COMP-2.
CCTEMP CHAR(10)
01 CCTEMP PIC X(10).
CCTEMP VARCHAR(80)
01 CCTEMP
49 VARLEN PIC S9(4) COMP.
49 CCVAR
PIC X(80).
5.
SQL Programming
IN DB2 operations are done using structured query language. This chapter
explains types of SQL and their usage. SQL statements are divided into
 DDL Statements
 DML Statements
 Control Statements
SQL PROGRAMMING
SQL (STRUCTURED QUERY LANGUAGE ) IS
THE LANGUAGE USED TO ACCESS DATA
IN DB2 TABLES
SQL
DDL
DML
CONTROL
STATEMENTS
 DDL (DATA DEFINITION LANGUAGE)



CREATE
ALTER
DROP
 DML (DATA MANIPULATION LANGUAGE)




SELECT
UPDATE
INSERT
DELETE
 CONTROL STATEMENTS




GRANT
REVOKE
COMMIT
ROLLBACK
5.1.
DDL Statements
Data definition language statements used for creating, changing and dropping
DB2 objects. The following sections explain these statements with suitable
examples
5.1.1. Create Database
5.1.2. Create Table Space
5.1.3. Create Table
5.1.3.1.Keys
5.1.3.2.Primary Keys
5.1.3.3.Foreign Keys
5.1.4. Create View
5.1.5. Create Index
5.1.6. Alter Table
5.1.7. Drop
CREATE DATABASE
THE CREATE DATABASE STATEMENT DEFINES A
DB2 DATABASE TO THE DB2 SUBSYSTEM. THE NAME
MUST NOT START WITH DSNDB AND MUST NOT
IDENTIFY AN EXISTING DATABASE
IN THIS STATEMENT YOU CAN SPECIFY THE NAME OF BUFFER
POOL AND STORAGE GROUP FOR TABLE SPACES AND INDEXES
WITHIN THE DATABASE
 IF BUFFER POOL IS NOT SPECIFIED IN THE CREATE DATABASE
STATEMENT THEN DEFAULT BUFFER POOL USED IS BP0.
 IF STORAGE GROUP IS NOT SPECIFIED IN THE CREATE DATABASE
STATEMENT THEN DEFAULT STORAGE GROUP USED IS SYSDEFLT.
 EXAMPLE
CREATE DATABASE "D2110K"
BUFFERPOOL BP2
STOGROUP "SGDB2O";
CREATE TABLESPACE
THE CREATE TABLESPACE STATEMENT ALLOCATES SPACE FOR
TABLES. THIS STATEMENT CREATES A SIMPLE, SEGMENTED,
OR PARTITIONED TABLE SPACE IN THE SPECIFIED DATABASE.
IF DATABASE IS NOT SPECIFIED THEN TABLESPACE IS CREATED
IN THE DEFAULT DATABASE DSNDB04
 EXAMPLES
1.
CREATE TABLESPACE "S110K10" IN "D2110K"
USING STOGROUP "SGDB2O"
PRIQTY 100 SECQTY 52
FREEPAGE 0 PCTFREE 5
BUFFERPOOL BP0
LOCKSIZE ANY
CLOSE NO
SEGSIZE 8;
2.
CREATE TABLESPACE "S110L40" IN "D2110L"
USING STOGROUP "SGDB2O"
PRIQTY 100 SECQTY 52
ERASE NO
NUMPARTS 16
FREEPAGE 0 PCTFREE 5
BUFFERPOOL BP2
LOCKSIZE PAGE
CLOSE NO;
Create Table Space
Many parameters can be specified in the CREATE TABLESPACE statement
which decides the type of tablespace, the SIZE of VSAM datasets which hold the
tables and indexes, the amount and distribution of space left free in the datasets,
the amount of data covered by concurrency control locks etc. All of these
decisions made during table space creation hold performance implications. If the
developer does not specify choices for any of these parameters DB2 will use
default values.
In the given examples DB2 automatically creates VSAM linear datasets needed
for the tablespace within the specified storage group. Each data set will be
defined on a volume of the storage group specified in the create tableapace
statement. The values specified for PRIQTY and SECQTY determine the primary
and secondary allocations for the data set.
Erase parameter Indicates whether the DB2-managed data sets for the
tablespace are to be erased when they are deleted during the execution of a
utility or an SQL statement that drops the table space. ERASE NO does not erase
the data sets. ERASE YES erases the data sets. As a security measure, DB2
overwrites all data in the data sets with zeros before they are deleted.
FREEPAGE parameter Specifies how often to leave a page of free space when
the table space or partition is loaded or reorganized. The default is FREEPAGE 0,
leaving no free pages. PCTFREE parameter indicates what percentage of each
page to leave as free space when the table is loaded or reorganized. The default
is PCTFREE 5.
LOCKSIZE parameter Specifies the size of locks used within the table space . For
more information please refer chapter 9.
NUMPARTS parameter Indicates that the table space will be partitioned and the
number of partitions in that tablespace.
BUFFERPOOL parameter Identifies the buffer pool to be used for the table space
and determines the page size of the table space.
CLOSE parameter specifies whether or not the data sets are eligible to be closed
when the table space is not being used or the limit on the number of open data
sets is reached. CLOSE YES says the dataset is eligible for closing. This is the
default. CLOSE NO specifies that the dataset is not eligible for closing.
SEGSIZE parameter Indicates that the table space will be segmented and
specifies, how many pages are to be assigned to each segment. If SEGSIZE and
NUMPARTS parameters are not given, then the table space will be SIMPLE
CREATE TABLE
CREATE TABLE STATEMENT CREATES A TABLE IN A
TABLESPACE. TABLE NAME IS UNIQUE FOR A USER.
IF USERA CREATES TABLEA THEN FULLY QUALIFIED
NAME WILL BE USERA.TABLEA. USERA CAN SIMPLY USE
THE NAME TABLEA BUT OTHER USERS MUST SPECIFY
FULLY QUALIFIED NAME
EXAMPLES
1.
CREATE TABLE D2110L.SP
(
,S# CHAR(5) NOT NULL
,P# CHAR(6) NOT NULL
,QTY INTEGER NOT NULL
,PRIMARY KEY( S# , P# )
,FOREIGN KEY ( S# ) REFERENCES S,
,FOREIGN KEY ( P# ) REFERENCES P
)
IN D2110L.TABSP
(2) CREATE TABLE D2110L.SP LIKE D2110K.TAB IN D2110L.TABSP;
KEYS
 A KEY IS ONE OR MORE COLUMNS THAT ARE IDENTIFIED AS
SUCH IN THE DESCRIPTION OF A TABLE, AN INDEX, OR A
REFERENTIAL CONSTRAINT.
S#
SNAME
S1
S2
S3
SMITH
JONES
BLAKE
STATUS
20
10
30
CITY
LONDON
PARIS
PARIS
KEY
 A KEY IDENTIFIES A ROW OF DATA
 A ROW IN ONE TABLE CAN CARRY THE KEY OF ANOTHER TABLE SO
KEYS ARE USED FOR RELATING TABLES
 A KEY COMPOSED OF MORE THAN ONE COLUMN IS CALLED A
COMPOSITE KEY. A COMPOSITE KEY IS AN ORDERED SET OF
COLUMNS OF THE SAME TABLE.
 A UNIQUE KEY IS A KEY THAT IS CONSTRAINED SO THAT NO TWO OF
ITS VALUES ARE EQUAL.
PRIMARY KEY
 A PRIMARY KEY IS A UNIQUE KEY THAT IS A PART OF THE
DEFINITION OF A TABLE
P#
P1
P2
P3
P4
P5
P6
PNAME
COLOR
NUT
BOLT
SCREW
SCREW
CAM
COG
RED
GREEN
BLUE
RED
BLUE
RED
WEIGHT
12
17
17
14
12
19
CITY
LONDON
PARIS
ROME
LONDON
PARIS
LONDON
PRIMARY KEY
 PRIMARY KEY OF A TABLE IS THE UNIQUE IDENTIFIER FOR THAT
TABLE
 PRIMARY KEY CAN BE COMPOSITE
 A TABLE CANNOT HAVE MORE THAN ONE PRIMARY KEY, AND THE
COLUMNS OF A PRIMARY KEY CANNOT CONTAIN NULL VALUES.
 WHEN A PRIMARY KEY IS DEFINED ON A TABLE, A UNIQUE INDEX
MUST BE CREATED ON THAT PRIMARY KEY
FOREIGN KEYS
 A FOREIGN KEY IS A COLUMN OR COMBINATION OF COLUMNS
IN ONE TABLE WHOSE VALUES ARE REQUIRED TO MATCH
VALUES OF THE PRIMARY KEY IN SOME OTHER TABLE.
TABLE S
S#
TABLE SP
SNAME
STATUS
CITY
S#
LONDON
PARIS
P#
QTY
S1
S2
SMITH
JONES
20
10
…..
………
…
PRIMARY KEY IN S
……
S1
S1
S2
….
P1
P2
P1
….
300
200
300
…..
FOREIGN KEY IN SP
 A FOREIGN KEY VALUE REPRESENTS A REFERENCE TO THE ROW
CONTAINING THE MATCHING PRIMARY KEY VALUE.
 THE TABLE THAT CONTAINS THE FOREIGN KEY IS KNOWN AS THE
DEPENDENT TABLE AND THE TABLE THAT CONTAINS THE PRIMARY
KEY IS KNOWN AS THE PARENT TABLE.
 EACH VALUE OF A FOREIGN KEY MUST BE WHOLLY NULL OR WHOLLY
NON NULL. THAT IS IF FOREIGN KEY IS A COMPOSITE KEY THEN ALL
COMPONENTS OF THAT KEY MUST BE NULL OR NON NULL, NOT A
MIXTURE.
CREATE VIEW
THE CREATE VIEW STATEMENT CREATES A
VIEW ON TABLES OR VIEWS. IF THE VIEW NAME
IS UNQUALIFIED THEN THE AUTHORIZATION ID
IS THE IMPLICIT QUALIFIER
BASE TABLE: S
S#
SNAME
STATUS
CITY
VIEW : GOOD_SUPPLIERS
S#
STATUS CITY
 IF YOU DO NOT SPECIFY A LIST OF COLUMN NAMES, THE COLUMNS
OF THE VIEW INHERIT THE NAMES OF THE COLUMNS OF THE RESULT
TABLE OF THE SUB SELECT.
EXAMPLE
CREATE VIEW GOOD_SUPPLIERS
AS SELECT S# , STATUS, CITY
FROM S
WHERE STATUS > 15 ;
CREATE INDEX
THE CREATE INDEX STATEMENT CREATES A PARTITIONED
OR NON PARTITIONED INDEX AND AN INDEX SPACE.
INDEX CAN BE CREATED ON ONE OR MORE COLUMNS.
WHEN YOU CREATE UNIQUE INDEX THE KEY CANNOT HAVE
DUPLICATE VALUES. UNIQUE INDEX SHOULD BE CREATED
FOR A PRIMARY KEY.
 EXAMPLES
1.
CREATE UNIQUE INDEX D2110K.I11010U1
ON D2110K.S
(S#)
BUFFERPOOL BP0
USING STOGROUP SGDB2O
PRIQTY 40
SECQTY 20
CLOSE NO;
2.
CREATE INDEX D2110P.I11010U2
ON D2110N.P (P# DESC)
3.
CREATE UNIQUE INDEX D2110L.I11010U3
ON D2110L.SP (S#, P#)
ALTER TABLE
THE ALTER TABLE STATEMENT CHANGES THE
DESCRIPTION OF A TABLE
TO ADD MULTIPLE COLUMNS ,CODE MULTIPLE ALTER
STATEMENTS.
ADDED COLUMNS MUST ACCEPT NULL OR NOT NULL
WITH DEFAULT VALUES
THIS COMMAND CANNOT BE USED FOR DELETING A COLUMN
PRIMARY AND FOREIGN KEYS CAN BE CREATED AND DROPPED
USING THIS COMMAND
 EXAMPLES
1.
ALTER TABLE D2110.P
ADD PRICE SMALLINT;
2.
ALTER TABLE D2110K.SP
FOREIGN KEY(P#) REFERENCES D2110K.P
ON DELETE CASCADE;
3
ALTER TABLE D2110K.P
PRIMARY KEY(P#);
4
ALTER TABLE D2110K.S
DROP PRIMARY KEY(S#);
DROP
THE DROP STATEMENT DELETES AN OBJECT
DROP
FREE
ALIAS alias name
DATABASE database name
INDEX
index name
STOGROUP stogroup name
SYNONYM synonym name
TABLE
table name
TABLESPACE
table space name
VIEW view name
PACKAGE collection-id.package-id
PLAN
 WHEN AN OBJECT IS DROPPED ALL OBJECTS THAT ARE DIRECTLY
OR INDIRECTLY DEPENDENT ON THAT OBJECT ARE DELETED
 THE OBJECT’S DESCRIPTION IS DELETED FROM THE CATALOG
TABLE.
Drop
The results of dropping various objects are given below.
1. Dropping an alias has no effect on any view or synonym that was defined
using the alias.
2. When you drop the database , the database and all of its table spaces, tables,
index spaces, and indexes are dropped.
3. Whenever an index is directly or indirectly dropped ,it’s index space is also
dropped.
4. When the synonym is dropped, view or alias that defined using the synonym
are not dropped.
5. Whenever a table is directly or indirectly dropped, all privileges on the table, all
referential constraints in which the table is a parent or dependent, and all
synonyms, views, and indexes defined on the table are also dropped.
6. Whenever a table space is directly or indirectly dropped, all tables in the table
space are also dropped.
7. Whenever a view is directly or indirectly dropped, all privileges on the view and
all synonyms and views that are defined on the view are also dropped.
8. when the package version is dropped, all privileges on the package are
dropped and all plans that are dependent on the execute privilege of the
package are invalidated.
5.2.
DML Statements
Data manipulation statements are used for retrieving data from DB2 tables. The
following statements together known as data manipulation language.
5.2.1. Select
5.2.1.1.Comparison Operators
5.2.1.2.Select Distinct
5.2.1.3.Multiple Conditions
5.2.1.4.Order By
5.2.1.5.In, Between
5.2.1.6.Partial Search
5.2.1.7.Aggregate Functions
5.2.1.8.Group By
5.2.1.9.Having
5.2.2. Joining Tables
5.2.3. Sub Queries
5.2.4. Union
5.2.5. Insert
5.2.6. Update
5.2.7. Delete
DML STATEMENTS
SELECT
SQL SELECT
REQUIRED SEQUENCE
SELECT
FROM
WHERE
ORDER BY
EXAMPLE
Q:
GET SUPPLIER NUMBERS AND STATUS FOR
SUPPLIERS IN PARIS, IN DESCENDING ORDER OF STATUS
QUERY
SELECT S# , STATUS
-TELLS WHICH COLUMNS TO USE
FROM S
-TELLS WHICH TABLES TO USE
WHERE CITY = ‘PARIS’
-TELLS WHICH ROWS TO USE
ORDER BY STATUS DESC ;
-TELLS HOW TO SEQUENCE THE RESULT
RESULT
S#
STATUS
S3
S2
30
10
COMPARISON OPERATORS
=
EQUAL
^=
NOT EQUAL
<>
NOT EQUAL
>
GREATER THAN
^>
NOT GREATER THAN
>=
GREATER THAN OR EQUAL
<
LESS THAN
^<
NOT LESS THAN
<=
LESS THAN OR EQUAL
SELECT DISTINCT
SELECT DISTINCT IS TO ELIMINATE DUPLICATE ROWS
Q
:
QUERY
RESULT
P#
P1
P2
P3
P4
P5
P6
GET PART NUMBERS FOR ALL PARTS SUPPLIED
WITH REDUNDANT DUPLICATES ELIMINATED
:
SELECT DISTINCT P#
FROM SP;
MULTIPLE CONDITIONS
MULTIPLE CONDITION RETRIEVAL
AND
OR
Q1 :
GET SUPPLIER NUMBERS AND SUPPLIER
NAMES OF SUPPLIERS LOCATED IN
LONDON AND HAVING STATUS CODE 20
Q2 :
GET SUPPLIER NUMBERS AND SUPPLIER
NAMES OF SUPPLIERS WHOSE STATUS IS 10
OR 20.
QUERY 1 :
SELECT S#, SNAME
FROM S
WHERE STATUS = 20
AND CITY = ‘LONDON’ ;
QUERY 2 :
SELECT S#, SNAME
FROM S
WHERE STATUS = 10
OR STATUS = 20 ;
RESULT 1
RESULT 2
S#
SNAME
S#
SNAME
S1
S4
SMITH
CLARK
S1
S2
S4
SMITH
JONES
CLARK
ORDER BY
SPECIFY COLUMN NAME AND TELL WHETHER
ASCENDING OR DESCENDING SEQUENCE
THE DEFAULT SEQUENCE IS ASCENDING
QUERY:
SELECT P# , ‘ WEIGHT IN GRAMS = ’ , WEIGHT * 454
FROM P
ORDER BY 3, P# ;
RESULT
P#
P1
P5
P4
P2
P3
P6
WEIGHT IN GRAMS
WEIGHT IN GRAMS
WEIGHT IN GRAMS
WEIGHT IN GRAMS
WEIGHT IN GRAMS
WEIGHT IN GRAMS
=
=
=
=
=
=
5448
5448
6356
7718
7718
8448
IN, BETWEEN
IN
:
TO MATCH ONE OF A LIST OF VALUES
BETWEEN:
TO SELECT A RANGE OF VALUES
CAN USE NOT
IN AND NOT BETWEEN
Q1
:
GET PART NUMBERS , PNAME AND WEIGHT OF
PARTS WHOSE WEIGHT IS ANY ONE OF THE
FOLLOWING: 12 ,16 ,17
Q2
:
GET PART NUMBERS , PNAME AND WEIGHT OF
PARTS WHOSE WEIGHT IS IN THE RANGE 16 TO
19 INCLUSIVE
QUERY 1
SELECT P# , PNAME , WEIGHT
FROM P
WHERE WEIGHT IN ( 12 , 16 , 17 ) ;
QUERY 2
SELECT P# , PNAME , WEIGHT
FROM P
WHERE WEIGHT BETWEEN 16 AND 19 ;
RESULT 1
P#
PNAME
P1
P2
P3
P5
NUT
BOLT
SCREW
CAM
RESULT 2
WEIGHT
12
17
17
12
P#
PNAME
P2
P3
P6
BOLT
SCREW
COG
WEIGHT
17
17
19
PARTIAL SEARCH
TO SEARCH ON A SUBSET OF CHARACTERS :
LIKE
NOT TO SEARCH ON A SUBSET OF CHARACTERS :
QUERY 1 :
SELECT S# , SNAME , CITY
FROM S
WHERE CITY LIKE ‘L%’ ;
QUERY 2 :
SELECT S# , SNAME , CITY
FROM S
WHERE SNAME LIKE ‘%S’ ;
QUERY 3 :
SELECT S# , SNAME , CITY
FROM S
WHERE CITY NOT LIKE ‘%A%’ ;
QUERY 4 :
SELECT S# , SNAME , CITY
FROM S
WHERE CITY LIKE ‘%DON’ ;
QUERY 5 :
SELECT S# , SNAME , CITY
FROM S
WHERE SNAME LIKE ‘_L%’ ;
NOT LIKE
RESULT 1
S#
SNAME
CITY
S1
S4
SMITH
CLARK
LONDON
LONDON
S#
SNAME
CITY
S2
S5
JONES
ADAMS
PARIS
ATHENS
RESULT 2
RESULT 3
S#
SNAME
S1
S4
SMITH
CLARK
CITY
LONDON
LONDON
RESULT 4
S#
SNAME
CITY
S1
S4
SMITH
CLARK
LONDON
LONDON
S#
SNAME
CITY
S3
S4
BLAKE
CLARK
RESULT 5
PARIS
LONDON
AGGREGATE FUNCTIONS
COUNT
:
NUMBER OF VALUES IN THE COLUMN
SUM
:
SUM OF VALUES IN THE COLUMN
AVG
:
AVERAGE OF VALUES IN THE COLUMN
MAX
:
MAXIMUM OF VALUES IN THE COLUMN
MIN
:
MINIMUM OF VALUES IN THE COLUMN
Q1
:
GET THE TOTAL NUMBER OF SUPPLIERS.
Q2
:
GET THE TOTAL QUANTITY, AVERAGE QUANTITY,
MAXIMUM QUANTITY AND MINIMUM QUANTITY OF
PART P2 SUPPLIED
QUERY 1
:
SELECT COUNT(*)
FROM S;
QUERY 2
:
SELECT SUM (QTY) , AVG (QTY) , MAX (QTY) , MIN (QTY)
FROM SP
WHERE P# = ‘P2’ ;
RESULT 1
5
RESULT 2
1000
250
400
200
GROUP BY
WITH GROUP BY, A COLUMN FUNCTION RESULTS
IN A SINGLE VALUE FOR EACH GROUP
Q
:
FOR EACH PART SUPPLIED GET THE PART
NUMBER AND THE TOTAL SHIPMENT QUANTITY
FOR THAT PART
QUERY
:
SELECT P# , SUM (QTY)
FROM SP
GROUP BY P# ;
RESULT
P#
P1
P2
P3
P4
P5
P6
600
1000
400
500
500
100
HAVING
HAVING IS USED TO GET SOME SPECIFIC ROWS, FROM THE ROWS
OBTAINED BY GROUP BY CLAUSE, WHICH SATISFY THE CONDITION
GIVEN IN THE HAVING CLAUSE.
HAVING IS USED TO ELIMINATE GROUPS JUST AS WHERE IS USED
TO ELIMINATE ROWS.
Q:
QUERY
GET PART NUMBERS FOR ALL PARTS SUPPLIED BY
MORE THAN ONE SUPPLIER
:
RESULT
P#
P1
P2
P4
P5
SELECT P#
FROM SP
GROUP BY P#
HAVING COUNT (*) > 1.
JOINING TABLES
IT IS A QUERY IN WHICH DATA IS RETRIEVED FROM MORE
THAN ONE TABLE
Q:
GET ALL COMBINATIONS OF SUPPLIER AND PART
INFORMATION SUCH THAT THE SUPPLIER CITY
FOLLOWS THE PART CITY IN ALPHABETICAL ORDER
QUERY :
SELECT S.* , P.*
FROM S , P
WHERE S.CITY > P.CITY
RESULT
S# SNAME STATUS S.CITY
P#
S2
S2
S2
S3
S3
S3
P1
P4
P6
P1
P4
P6
JONES
JONES
JONES
BLAKE
BLAKE
BLAKE
10
10
10
30
30
30
PARIS
PARIS
PARIS
PARIS
PARIS
PARIS
PNAME COLOR WEIGHT P.CITY
NUT
SCREW
COG
NUT
SCREW
COG
RED
RED
RED
RED
RED
RED
12
14
19
12
14
19
LONDON
LONDON
LONDON
LONDON
LONDON
LONDON
SUB QUERIES
A SUB QUERY IS A SELECT-FROM-WHERE EXPRESSION
THAT IS NESTED INSIDE ANOTHER SUCH EXPRESSION
MAXIMUM 15 LEVELS ARE POSSIBLE IN A NESTED SUB
SELECT
Q:
GET SUPPLIER NAMES FOR SUPPLIERS WHO SUPPLY
PART P2.
QUERY :
RESULT
SNAME
SMITH
JONES
BLAKE
CLARK
SELECT SNAME
FROM S
WHERE S# IN
( SELECT S#
FROM SP
WHERE P# = ‘P2’ ) ;
UNION
THE RESULTS OF ONE OR MORE RELATIONS ARE
MIXED TO FORM A SINGLE RELATION USING UNION .
Q:
GET PART NUMBERS FOR PARTS THAT EITHER
WEIGH MORE THAN 16 POUNDS OR ARE
SUPPLIED BY SUPPLIER S2
QUERY :
SELECT P#
FROM P
WHERE WEIGHT > 16
UNION
SELECT P#
FROM SP
WHERE S# = ‘S2’ ;
RESULT
P1
P2
P3
P6
INSERT
THE INSERT STATEMENT INSERTS A NEW ROW INTO
THE TABLE. YOU CAN EITHER INSERT VALUES FOR
ALL COLUMNS OR OMIT VALUES. BUT OMITTING A
A VALUE FOR SOME COLUMN DEPENDS ON THE
WAY THE COLUMN WAS DEFINED
Q1 :
ADD PART P8 (A SPROCKET , COLOR PINK ,
WEIGHT 14 , CITY NICE ) TO TABLE P
Q2 :
ADD PART P7 (CITY ATHENS , WEIGHT 24 ) NAME
AND COLOR AT PRESENT UNKNOWN. ASSUME
THAT THE COLUMNS PNAME AND COLOR ARE
CREATED WITH NULL ATTRIBUTE SPECIFICATION.
QUERY 1
:
INSERT
INTO P
VALUES ( ‘P8’, ‘SPROCKET’, ‘PINK’, 14, ‘NICE’ ) ;
QUERY 2
:
INSERT
INTO P ( P#, CITY, WEIGHT )
VALUES ( ‘P7’, ‘ATHENS’, 24 );
P#
…
P8
P7
PNAME
….
SPROCKET
?
COLOR WEIGHT
CITY
…
PINK
?
…….
NICE
ATHENS
....
14
24
RESULT 1
RESULT 2
UPDATE
THE UPDATE STATEMENT UPDATES THE VALUES
OF SPECIFIED COLUMNS IN ROWS OF A TABLE OR
VIEW. UPDATING A ROW OF A VIEW UPDATES A
ROW OF THE TABLE ON WHICH THE VIEW IS BASED.
Q:
QUERY
CHANGE THE COLOR OF PART P1 TO YELLOW ,
INCREASE IT’S WEIGHT BY 5 , AND SET IT’S CITY
TO UNKNOWN. ASSUME THAT THE DEFINITION
OF P.CITY ALLOWS NULL VALUES.
:
UPDATE P
SET COLOR = ‘YELLOW’ ,
WEIGHT = WEIGHT + 5
CITY = NULL
WHERE P# = ‘P1’ ;
RESULT
P#
…
P1
…
PNAME
…
NUT
…
COLOR WEIGHT
…
…
YELLOW
17
…
…
CITY
…
?
…
DELETE
THE DELETE STATEMENT DELETES ROWS FROM
A TABLE OR VIEW. DELETING A ROW FROM A
VIEW DELETES THE ROW FROM THE TABLE ON
WHICH THE VIEW IS BASED.
SINGLE ROW DELETE
Q1:
DELETE SUPPLIER S5
MULTIPLE ROW DELETE
Q2 :
DELETE ALL SHIPMENTS WITH QUANTITY
GREATER THAN 300
QUERY 1
:
DELETE
FROM S
WHERE S# = ‘S5’ ;
QUERY 2
:
DELETE
FROM SP
WHERE QTY > 300 ;
5.3.
Control Statements
Statements other than DDL and DML are explained in this section. They are
5.3.1. Grant
5.3.2. Revoke
5.3.3. Commit
5.3.4. Roll Back
CONTROL STATEMENTS
GRANT
TO PERFORM ANY OPERATION ON ANY OBJECT THE
USER MUST HOLD THE APPROPRIATE PRIVILEGE
FOR THE OPERATION AND THE OBJECT IN QUESTION .
THE GRANT STATEMENT GRANTS PRIVILEGES ON AN
OBJECT TO AUTHORIZATION IDS.
TABLE PRIVILEGES
GRANT SELECT ON TABLE S TO CHARLY ;
GRANT SELECT , UPDATE (STATUS , CITY ) ON TABLE S
TO JUDY, JACK, JOHN ;
GRANT ALL PRIVILEGES ON TABLE S TO PUBLIC ;
PACKAGE AND PLAN PRIVILEGES
GRANT EXECUTE ON PLAN PLANB TO CHARLY ;
COLLECTION PRIVILEGES
GRANT CREATE IN EWSK TO JOHN ;
DATABASE PRIVILEGES
GRANT CREATETAB ON DATABASE DBX TO NANCY ;
USE PRIVILEGES
GRANT USE OF TABLESPACE DBX.TS76 TO TOM ;
SYSTEM PRIVILEGES
GRANT CREATEDBC TO ARNOLD ;
REVOKE
USED TO REVOKE PREVIOUSLY GRANTED PRIVILEGES ON AN
OBJECT FROM USERS. GENERAL FORMAT OF REVOKE IS
SIMILAR TO THAT OF GRANT. REVOKE CAN BE USED TO
REVOKE ALL PRIVILEGES EXPLAINED IN THE GRANT COMMAND
EXAMPLES
REVOKE SELECT ON TABLE S FROM CHARLY ;
REVOKE UPDATE ON TABLE S FROM JOHN ;
REVOKE CREATETAB ON DATABASE DBX FROM NANCY ;
COMMIT
COMMIT OPERATES ON A UNIT OF RECOVERY
AFTER EXECUTING THIS STATEMENT
 ALL CHANGES WILL BE DONE PERMANENTLY
 ROW LOCKS WILL BE RELEASED
 DEFAULT COMMIT IS AT PROGRAM TERMINATION
 IF AN APPLICATION DETERMINES THAT A UNIT OF WORK IS
SUCCESSFUL IT CAN INDICATE THAT TO THE DATABASE MANAGER
VIA A COMMIT. THE DATABASE MANAGER CAN MAKE THE CHANGES
PERMANENT
 CURSORS ARE CLOSED EXCEPT THOSE DECLARED WITH HOLD
OPTION
EXAMPLE
UPDATE TABLE S
SET STATUS = 20
WHERE S# = S1;
COMMIT;
ROLLBACK
A UNIT OF WORK IS UNDONE IF ANY ABNORMAL
CONDITION OCCURS . WHEN THIS STATEMENT
IS EXECUTED
 ALL CHANGES IN THAT UNIT OF WORK
WILL BE BACKED OUT
 ALL LOCKS ARE RELEASED
 ALL OPEN CURSORS ARE CLOSED
 WHEN YOU ISSUE A ROLLBACK THEN THE DATABASE MANAGER WILL
RE-ESTABLISH THE STATE OF THE DATABASE AT THE LAST
COMPLETED UNIT OF WORK
 ROLLBACK WILL BE DONE EITHER BY THE PROGRAM OR BY THE
SYSTEM.
EXAMPLE
ROLLBACK WORK ;
6.
Program Structure
This section gives an over view of a DB2 application program .Different sections
to be included in an application are explained briefly.
6.1.
Host Variables
6.1.1. Declaring Host Variables
6.2.
Indicator Variables
6.3.
SQLCA
6.4.
Cobol Structure Of SQLCA
6.5.
SQLCA Return Codes
6.6.
SQLCA Warnings
6.7.
Important SQL codes
6.8.
Static SQL
6.9.
Dynamic SQL
6.10. Example For A DB2 Application Program
PROGRAM STRUCTURE
STRUCTURE OF A PROGRAM THAT ACCESSES DB2
SQLCA
HOST VARIABLE DECLARATIONS
DECLARE TABLE STATEMENTS
DECLARE CURSOR
SQL STATEMENTS WITHOUT
FETCH
OPEN CURSOR
FETCH CURSOR
CLOSE CURSOR
 DIFFERENT SECTIONS TO BE INCLUDED IN A DB2 PROGRAM ARE
SHOWN IN THE ABOVE FIGURE.
 IF THE HOST LANGUAGE IS COBOL, THEN HOST VARIABLE
DECLARATION, SQLCA, AND DECLARE TABLE STATEMENTS SHOULD
BE IN THE WORKING STORAGE SECTION AND CURSOR
DECLARATIONS SHOULD BE JUST ABOVE THE PROCEDURE DIVISION.
ALL OTHER SECTIONS ARE IN PROCEDURE DIVISION.
Program Structure
Programs that access DB2 are written in a number of host languages - COBOL,
PL/1, C , ASSEMBLER , FORTRAN, BASIC etc. These programs can contain
SQL statements that retrieves or updates database.
The start and end of SQL statements must be indicated by delimiters. The
delimiters used in COBOL are EXEC SQL and END-EXEC.
SQL statements must be coded with in these delimiters. Even if multiple SQL
statements appear sequentially, each SQL statement should be indicated by
delimiters.
Pre compiler uses delimiters to identify SQL statements from the host language.
EXAMPLE OF USING DELIMITERS IN COBOL
EXEC SQL
UPDATE S
SET STATUS = 10
WHERE CITY = ‘ATHENS’
END-EXEC.
HOST VARIABLES
HOST VARIABLES ARE USED TO IDENTIFY THE SYMBOLIC
NAME OF STORAGE, THAT HAS BEEN DECLARED USING
THE APPLICATION PROGRAM LANGUAGE DEFINITION STATEMENT
SQL STATEMENT
SELECT SNAME INTO :TMPNAME WHERE S# = ‘S1’
HOST VARIABLE
 HOST VARIABLES ARE OPTIONAL
 HOST LANGUAGE VARIABLES IN SQL STATEMENT MUST BE
PRECEDED BY A COLON
 HOST VARIABLE MUST MATCH COLUMN DATA TYPE
 CAN BE USED ANYWHERE A VALUE IS REQUIRED IN AN SQL
STATEMENT
EXAMPLE(1)
 SQL STATEMENT 1
INSERT INTO S
( S#, SNAME )
VALUES ( ‘S6’ , ‘GEORGE’ )
 SQL STATEMENT 2
INSERT INTO S
( S#, SNAME )
VALUES ( :SUPCODE, :SUPNAME )
In SQL statement 1 the values to be inserted are hard coded .Second SQL
statement shows the use of host variables in an embedded SQL .This statement
could be included in a processing loop with the program’s logic assigning various
values to the host variables.
EXAMPLE (2)
 SQL STATEMENT
UPDATE S
SET STATUS = STATUS * :PERCENT
WHERE S# = :SUPCODE
In this example host variables are used to update a table .
DECLARING HOST VARIABLES
THERE ARE TWO METHODS OF HOST VARIABLE DECLARATION
(1) DECLARE HOST VARIABLES IN THE WORKING STORAGE SECTION
(2) EXEC SQL
INCLUDE (member name which contains all host variable declarations
and declare table statements)
END EXEC.
Declaring Host Variables
You can declare all host variables in the working storage section of the COBOL
program. The host variable declaration should match with the corresponding
column definition
The host variable names must not begin with SQL or EXEC.
Another method of declaring host variables is using the verb INCLUDE. All the
host variables are declared in a partitioned dataset member and that member is
included in the source program using verb INCLUDE.
INDICATOR VARIABLES
INDICATOR VARIABLE INDICATES THE PRESENCE
OF NULL VALUE IN A COLUMN
SELECT SNAME INTO :SUPNAME:SUPNAMIND
FROM S
HOST VARIABLE
INDICATOR VARIABLE
 INDICATOR VARIABLE IS REQUIRED IF THE SELECTED COLUMNS
ALLOWS NULL
 IF COLUMN CONTAINS NULL VALUE THEN THE INDICATOR VARIABLE
IS SET TO NEGATIVE VALUE, HOST VARIABLE IS UNTOUCHED
 INDICATOR VARIABLE IS ASSOCIATED WITH A HOST VARIABLE
Indicator Variables
When the program is to receive a value from a column that allows nulls, the
program can get either a value or null. So the program requires two variables, a
host variable to receive value and an indicator variable to indicate the presence of
null value in the selected column.
If DB2 attempts to indicate the presence of a null and the program does not
provide an indicator variable an error occurs.
If the value returned is null then the null indicator indicates that by a negative
value and the value in the host variable remains unchanged. The program should
have an indicator variable for each column that allows null.
In EXAMPLE1 when the selected column contains a null value then the program
logic is coded in such way to tackle it.
Example 2 shows that indicator variables are used for UPDATE operations also.
Before updating the table, the indicator variable is made negative and DB2 sets
the column to null ignoring the value in the host variable.
Indicator variable should be declared like you declare a host variable. Data type of
an indicator variable is SMALLINT and corresponding cobol declaration is given
below
01 SUPNAMIND PIC S9(4) COMP.
Examples
1.
EXEC SQL
SELECT SNAME , CITY
INTO :SUPNAME:SUPNAMIND , :PGMCITY
FROM S
WHERE S# = ‘ S1’
END EXEC.
IF SUPNAMIND < 0
PERFORM NONAME-SECTION
ELSE
PERFORM NAME-SECTION.
2.
IF ( some condition )
SUPNAMIND = -1
ELSE
SUPNAMIND = 0.
EXEC SQL
UPDATE S
SET SNAME = :SUPNAM:SUPNAMIND
WHERE S# = ‘S1’
END EXEC.
SQLCA ( SQL COMMUNICATION AREA)
THE SUCCESS OR FAILURE OF THE LAST EXECUTED SQL
STATEMENT IS DESCRIBED IN SQLCA
PROGRAM
STATUS OF EXECUTED SQL
SQLCA
SQL STATEMENTS
DB2
 AFTER EACH SQL STATEMENT, SQLCA CODES MUST BE CHECKED BY
THE PROGRAM TO FIND WHETHER THE SQL WAS SUCCESSFUL OR
NOT
 SQLCA IS INCORPORATED IN THE PROGRAM USING INCLUDE
STATEMENT.
SQLCA
The SQL communication area (SQLCA) is a data structure that must be included
in any host language program using SQL .The SQLCA provides a way for DB2 to
pass feedback about it’s operations to the program .After executing an SQL DB2
returns via the SQLCA ,codes indicating the execution was successful or
identifying errors and special conditions. The program can then test for these
codes and react according to their content.
The SQLCA structure contains variables for a number of codes and messages.
Programmers can code the necessary structure(explained in next page) , copy it
from a source library or have DB2 generate it.
An include statement allows the source program to include SQLCA structure from
the copy library and is shown below.
EXEC SQL
INCLUDE SQLCA
END EXEC.
COBOL STRUCTURE OF SQLCA
01 SQLCA.
05 SQLCAID
PIC X(8).
05 SQLCABC
PIC S9(9) COMP-4.
05 SQLCODE
PIC S9(9) COMP-4.
05 SQLERRM.
49 SQLERRML PIC S9(4) COMP-4.
49 SQLERRMC PIC X(70).
05 SQLERRP
PIC X(8).
05 SQLERRD
OCCURS 6 TIMES
PIC S9(9) COMP-4.
05 SQLWARN.
10 SQLWARN0 PIC X.
10 SQLWARN1 PIC X.
10 SQLWARN2 PIC X.
10 SQLWARN3 PIC X.
10 SQLWARN4 PIC X.
10 SQLWARN5 PIC X.
10 SQLWARN6 PIC X.
10 SQLWARN7 PIC X.
05 SQLEXT.
10 SQLWARN8 PIC X.
10 SQLWARN9 PIC X.
10 SQLWARNA PIC X.
10 SQLSTATE PIC X(5).
 MOST IMPORTANT SQLCA CODES ARE SQLCODE AND SQLWARN0
SQLCA RETURN CODES
CONDITION
STATUS
INTEGER
SQLCODE
ERROR
<0
WARNING
>0 & <>100
NOT FOUND
+100
SUCCESS
0
CHAR(1)
SQLWARN0
REQUEST
FAILED
OR ‘W’
SATISFIED
WITH SPECIAL
CONDITION
DATA NOT
FOUND
AND ‘ ‘
SUCCESS
 IF SQLCODE CONTAINS A NEGATIVE VALUE THEN IT IS AN ERROR
 ALL POSITIVE SQLCODES NOT EQUAL TO 100 ARE CONSIDERED
WARNINGS
 A ‘W’ IN SQLWRN0 INDICATES A WARNING EVEN IF SQLCODE = 0.
SQLCA WARNINGS
SQL WARNING
DESCRIPTION
SQLWARN0
THIS FIELD IS BLANK IF ALL SQL WARNINGS
FROM SQLWARN1 TO SQLWARNA ARE BLANKS.
CONTAINS ‘W’ IF ONE OR MORE SQL WARNINGS
CONTAINS W.
SQLWARN1
CONTAINS W IF THE VALUE OF A STRING COLUMN
WAS TRUNCATED WHEN ASSIGNED TO HOST
VARIABLE.
SQLWARN2
CONTAINS W IF NULL VALUES WERE ELIMINATED
FROM THE ARGUMENT OF A COLUMN FUNCTION
SQLWARN3
CONTAINS W IF THE NUMBER OF RESULT COLUMNS
IS LARGER THAN THE NUMBER OF HOST VARIABLES.
SQLWARN4
CONTAINS W IF A PREPARED UPDATE OR DELETE
STATEMENT DOES NOT INCLUDE A WHERE CLAUSE.
SQLWARN5
CONTAINS W IF THE SQL STATEMENT WAS NOT
EXECUTED BECAUSE IT IS NOT A VALID SQL
STATEMENT IN DB2 FOR MVS/ESA.
SQLCA WARNINGS…..
SQL WARNING
DESCRIPTION
SQLWARN6
CONTAINS W IF THE ADDITION OF A MONTH OR YEAR
DURATION TO A DATE OR TIMESTAMP VALUE
RESULTS IN AN INVALID DAY. AN INVALID DAY (FOR
EXAMPLE, JUNE 31). INDICATES THAT THE VALUE OF
THE DAY WAS CHANGED TO THE LAST DAY OF THE
MONTH TO MAKE THE RESULT VALID.
SQLWARN7
CONTAINS A W IF ONE OR MORE NON ZERO DIGITS
WERE LIMITED FROM THE FRACTIONAL PART OF
A NUMBER USED AS THE OPERAND OF A DECIMAL
MULTIPLY OR DIVIDE OPERATION.
SQLWARN8
CONTAINS A W IF A CHARACTER THAT COULD NOT
BE CONVERTED WAS REPLACED WITH A
SUBSTITUTE CHARACTER.
SQLWARN9
CONTAINS A W IF ARITHMETIC EXCEPTIONS WERE
IGNORED DURING COUNT DISTINCT PROCESSING.
SQLWARNA
CONTAINS A W IF AT LEAST ONE CHARACTER FIELD
OF THE SQLCA OR THE SQLDA NAMES OR LABELS IS
INVALID DUE TO A CHARACTER CONVERSION ERROR.
Important SQL codes
-102 LITERAL STRING IS TOO LONG. STRING BEGINS string
-107 THE NAME name IS TOO LONG. MAXIMUM ALLOWABLE SIZE IS size
-117 THE NUMBER OF INSERT VALUES IS NOT THE SAME AS THE
NUMBER OF OBJECT COLUMNS
-119 A COLUMN IDENTIFIED IN A HAVING CLAUSE IS NOT INCLUDED IN
THE GROUP BY CLAUSE
-125 AN INTEGER IN THE ORDER BY CLAUSE DOES NOT IDENTIFY A
COLUMN OF THE RESULT
-150 THE OBJECT OF THE INSERT, DELETE, OR UPDATE STATEMENT IS
A VIEW FOR WHICH THE REQUESTED OPERATION IS NOT PERMITTED
-204 name IS AN UNDEFINED NAME
-205 column-name IS NOT A COLUMN OF TABLE table-name
-303 A VALUE CANNOT BE ASSIGNED TO OUTPUT HOST VARIABLE
NUMBER position-number BECAUSE THE DATA TYPES ARE NOT
COMPARABLE
-401 THE OPERANDS OF AN ARITHMETIC OR COMPARISON OPERATION
ARE NOT COMPARABLE
-407 AN UPDATE OR INSERT VALUE IS NULL, BUT THE OBJECT COLUMN
column-name CANNOT CONTAIN NULL VALUES
-501 THE CURSOR IDENTIFIED IN A FETCH OR CLOSE STATEMENT IS
NOT OPEN
-502 THE CURSOR IDENTIFIED IN AN OPEN STATEMENT IS ALREADY
OPEN
-503 A COLUMN CANNOT BE UPDATED BECAUSE IT IS NOT IDENTIFIED
IN THE UPDATE CLAUSE OF THE SELECT STATEMENT OF THE CURSOR
-504 THE CURSOR NAME cursor-name IS NOT DEFINED
-540 THE DEFINITION OF TABLE table-name IS INCOMPLETE BECAUSE IT
LACKS A PRIMARY INDEX OR A REQUIRED UNIQUE INDEX
-551 auth-id DOES NOT HAVE THE PRIVILEGE TO PERFORM OPERATION
operation ON OBJECT object-name
-603 A UNIQUE INDEX CANNOT BE CREATED BECAUSE THE TABLE
CONTAINS ROWS WHICH ARE DUPLICATES WITH RESPECT TO THE
VALUES OF THE IDENTIFIED COLUMNS
-623 A CLUSTERING INDEX ALREADY EXISTS ON TABLE table-name
-661 INDEX index-name CANNOT BE CREATED ON PARTITIONED TABLE
SPACE tspace-name BECAUSE THE NUMBER OF PART SPECIFICATIONS IS
NOT EQUAL TO THE NUMBER OF PARTITIONS OF THE TABLE SPACE
-672 OPERATION DROP NOT ALLOWED ON TABLE table_name
-719 BIND ADD ERROR
USING auth-id AUTHORITY
PACKAGE package-name
ALREADY EXISTS
-805 DBRM
or
PACKAGE
NAME
location-name.collection-id.dbrmname.consistency -token NOT FOUND IN PLAN plan-name. REASON reason
-811 THE RESULT OF AN EMBEDDED SELECT STATEMENT IS A TABLE OF
MORE THAN ONE ROW, OR THE RESULT OF THE SUBQUERY OF A BASIC
PREDICATE IS MORE THAN ONE VALUE
-904 UNSUCCESSFUL EXECUTION CAUSED BY AN UNAVAILABLE
RESOURCE. REASON reason-code, TYPE OF RESOURCE resource-type, AND
RESOURCE NAME resource-name
-911 THE CURRENT UNIT OF WORK HAS BEEN ROLLED BACK DUE TO
DEADLOCK OR TIMEOUT. REASON reason-code, TYPE OF RESOURCE
resource-type, AND RESOURCE NAME resource-name
-913 UNSUCCESSFUL EXECUTION CAUSED BY DEADLOCK OR TIMEOUT.
REASON CODE reason-code, TYPE OF RESOURCE resource-type, AND
RESOURCE NAME resource-name
CODING AIDS
WHENEVER STATEMENT
EXEC SQL
WHENEVER Condition Action
END-EXEC
 CONDITION:
SQLERROR
-- NEGATIVE SQLCODE
SQLWARNING
-- POSITIVE SQLCODE ( NOT +100 )
-- OR SQLWARN0 = ‘W’
NOT FOUND
-- SQLCODE = +100
 ACTION:
GO TO :SECTA
-- CONTROL TRANSFERRED TO STATEMENT LABELED
SECTA
CONTINUE
-- PROGRAM CONTINUES WITH NEXT STATEMENT
-- USED TO CANCEL THE EFFECT OF PRIOR
WHENEVER
 PHYSICAL PLACEMENT OF WHENEVER STATEMENT DETERMINES THE
SQL STATEMENTS UNDER IT’S EFFECT
 THE USE OF COLON BEFORE THE LABEL IS OPTIONAL
 ‘’ GO TO ‘’ AND ‘’ GOTO ’’ ARE EQUIVALENT
Whenever Statement
WHENEVER statements help programmers to avoid checking SQLCODE after
every SQL statement. WHENEVER statements are SQL STATEMENTS that can
be embedded in one or more times in the host language program for branching to
a paragraph depending on the content of SQLCODE.
Each WHENEVER statement applies to all of the SQL statements that follow it in
the program listing, regardless of order in which the statements are actually
executed. This happens because COBOL precompiler puts appropriate branching
instruction after every SQL statement that follows the whenever statement.
WHENEVER statements can be used for three different conditions and these are
similar to IF THEN statements. IF SQLcode satisfies some condition then the
program performs the branching .
EXAMPLE
EXEC SQL
WHENEVER NOT FOUND CONTINUE
END-EXEC
EXEC SQL
WHENEVER SQLERROR PERFORM ERR-SECTION
END-EXEC
EXEC SQL
WHENEVER SQLWARNING PERFORM WARN-SECTION
END-EXEC
INCLUDE STATEMENT
THE INCLUDE STATEMENT INSERTS DECLARATIONS
OR CODE INTO A SOURCE PROGRAM.
SOURCE PROGRAM
EXEC SQL
SQLCA (TO BE INCLUDED IN SOURCE
PROGRAM )
01SQLCA
05 SQLCAID
05 SQLCABC
PIC X(8).
PIC S9(9) COMP-4.
INCLUDE SQLCA
END-EXEC.
 THE INCLUDE STATEMENT INSERTS SOURCE CODE INTO A SOURCE
PROGRAM AT PRE COMPILE TIME.
 THE INCLUDE STATEMENT CANNOT REFER TO SOURCE STATEMENTS
THAT THEMSELVES CONTAIN INCLUDE STATEMENTS.
USING CURSORS
PROCESSING MULTIPLE ROWS
QUERY:
SELECT STATUS, CTTY INTO :RANK, :CITY
FROM S WHERE STATUS < 30 ;
STATUS
2
10
20
CITY
LONDON
PARIS
LONDON
RANK
STATUS
CITY
20
10
20
LONDON
PARIS
LONDON
STATUS
20
10
20
CITY
RANK
CITY
RANK
CITY
CITY
LONDON
PARIS
LONDON
Processing Multiple Rows
In previous example the result of the query gives multiple rows. But there is no
method to determine the number of rows satisfying the condition before actually
receiving data from DB2.Therefore it is not possible to allocate storage in the
application program to receive an entire set of data.
When we are using host variables for retrieving data and if the result is a single
row the query will work and SQL return code will be set to zero. But in the given
example the result of the query gives multiple rows and the host language can
deal with only at a time Now the program is in error, SQLCODE will be set to a
negative value and the values of the host variables will be unpredictable.
DB2 provides the use of cursors to process SETS of data. The cursor is used to
retrieve all rows in the SET one by one. Each fetch of the cursor retrieves the next
row in the set of data that meets the condition.
SELECT WITH FETCH
 DEFINE A CURSOR
EXEC SQL
DECLARE CURSOR K10 FOR
SELECT SNAME, CITY
FROM S
WHERE STATUS < 30
END-EXEC
DEFINITION
 OPEN THE CURSOR
EXEC SQL
OPEN K10
END-EXEC
 FETCH RESULT ROWS ONE AT A TIME
EXEC SQL
FETCH K10 INTO :SUPNAME, :CITY
END-EXEC
EXECUTION
 CLOSE CURSOR WHEN FINISHED
EXEC SQL
CLOSE K10
END-EXEC
 THE DECLARE CURSOR STATEMENT RELATES A CURSOR TO A
SELECT STATEMENT
 OPEN CURSOR STATEMENT GENERATES EXECUTABLE CODE.
 FETCH CURSOR STATEMENT RETRIEVES A ROW FROM A SET OF
DATA
 CLOSE CURSOR STATEMENT DEACTIVATES THE CURSOR
Select With Fetch
DECLARE cursor statement defines a cursor with the specified name with an
associated query as specified by the select that forms part of that declare. The
declare cursor statement is not an executable code, but a purely declarative
statement. A program can use any number of DECLARE CURSOR statements,
and each of which must be of a different name.
Open cursor statement generates executable code. The select clause used in the
DECLARE CURSOR statement is effectively executed when the cursor is
opened. This is done using the current value of the host variable (if used).
This executable code will allow subsequent fetch statements to access the set of
data that meets the definition of the DECLARE CURSOR‘s underlying SELECT
statement. Opening the cursor is a must and DB2 will not open it on the first fetch.
The FETCH statement will retrieves a row of data from the set made accessible
by the open statement. Data is retrieved in host variables specified after the INTO
clause of FETCH statement. After the first FETCH statement which retrieves the
first row, the cursor will be advanced to the next row during the second FETCH
operation and then assigns values from that row to host variables.
After retrieving the required rows the CURSOR can be closed. The CLOSE
CURSOR statement releases the cursor from the set of data.
UPDATE USING A CURSOR
EXEC SQL
DECLARE CURSOR K10 FOR
SELECT SNAME, CITY
FROM S
WHERE STATUS = :RANK
FOR UPDATE OF CITY
END-EXEC
EXEC SQL
OPEN K10
END-EXEC
EXEC SQL
FETCH K10 INTO :SUPNAME, :CITY
END-EXEC
EXEC SQL
UPDATE S
SET CITY = :NEWCITY
WHERE CURRENT OF K10
END-EXEC
EXEC SQL
CLOSE K10
END-EXEC
 DECLARE CURSOR HAS AN ADDITIONAL
CLAUSE.
FOR UPDATE OF
 DECLARE, OPEN, FETCH and CLOSE CURSOR LOGIC IS NOT CHANGED
 UPDATE WHERE CURRENT OF cursor name UPDATES THE ROW
PRESENTLY IDENTIFIED BY THE CURSOR
Update Using A Cursor
The usual logic of cursors is used for updating a row which is present in the set of
data, satisfying the select statement in the DECLARE CURSOR. The columns
that may be updated are specified using FOR UPDATE OF clause in the
DECLARE CURSOR statement.
The update operation is done after fetching a row from the SET of data. This type
of update is useful where the retrieved row is required for the program before
updating it. UPDATE WHERE CURRENT OF CURSOR clause updates the row
where the cursor is presently positioned. The next row can be updated only after
issuing another FETCH.
Requirement of specifying FOR UPDATE OF clause for updating a table using
CURSORS depends on the pre compiler option given. If pre compiler NOFOR
option is specified then FOR UPDATE OF clause is not required. If NOFOR is not
specified FOR UPDATE OF CLAUSE is required and an attempt to update a
column not mentioned in that column will fail at run time.
DELETE USING A CURSOR
EXEC SQL
DECLARE CURSOR K10 FOR
SELECT SNAME, CITY
FROM S
WHERE STATUS = :RANK
FOR UPDATE OF CITY
END-EXEC
EXEC SQL
OPEN K10
END-EXEC
EXEC SQL
FETCH K10 INTO :SUPNAME, :CITY
END-EXEC
EXEC SQL
DELETE FROM S
WHERE CURRENT OF K10
END-EXEC
EXEC SQL
CLOSE K10
END-EXEC
 THE DECLARE, OPEN, FETCH and CLOSE CURSOR LOGIC IS NOT
CHANGED
 DELETE WHERE CURRENT OF cursor DELETES THE ROW PRESENTLY
POSITIONED BY THE CURSOR
 THIS FORM OF DELETE WILL BE USED IF THE DATA CONTAINED IN A
ROW IS NEEDED BY THE APPLICATION BEFORE IT IS DELETED.
STATIC SQL
PLAN
TO SELECT DATA
PROGRAM
PLAN
DB2
* SELECT
CALL
SELECT
RESULT

TABLE
PROGRAM HANDLES THE RESULT
 STATEMENT
PROGRAMMER KNOWS THE SQL STATEMENT TO BE USED
AND ALWAYS DOES THE SAME FUNCTION ON THE SAME
TABLES AND COLUMNS.
 BIND



ON ALL SQL STATEMENTS
BEFORE PROGRAM EXECUTION
BUILDS A STORED PLAN
 AUTHORIZATION
 HELD BY THE PLAN BINDER
DYNAMIC SQL
TO EXECUTE USER’S REQUEST
PLAN
PROGRAM
PLAN
PREPARE
DB2
EXECUTE
CALL
EXECUTE
TABLE
RESULT
PROGRAM HANDLES THE RESULT
 STATEMENT
SQL STATEMENTS ARE PREPARED AT RUN TIME AND
EXECUTED. TARGET TABLE OR COLUMN CAN BE SPECIFIED
AT RUN TIME
 BIND



ON SINGLE STATEMENT
AT STATEMENT EXECUTION
ACCESS STRATEGY NOT SAVED
 AUTHORIZATION

HELD BY THE PROGRAM EXECUTOR
Example For Dynamic SQL
01 STMT
49 LEN PIC S9(4) COMP.
49 TEXT PIC X(200).
01 X PICX(6).
01 Y PICX(6).
01 Z PIC X(6).
……………
……………
……………
EXEC SQL DECLARE SS STATEMENT END-EXEC
EXEC SQL DECLARE CC CURSOR FOR SS END-EXEC
……………
……………
MOVE WS-TEXT TO TEXT:
MOVE LENGTH-OF-TEXT TO LEN
(SELECT CL1,CL2,CL3 FROM T1 WHERE CL1 = 1932)
EXEC SQL PREPARE SS FROM :STMT END-EXEC
EXEC SQL OPEN CC END-EXEC
EXEC SQL FETCH CC INTO :X, :Y, :Z END-EXEC
( repeat fetch until sqlcode 100)
…………………
………………….
EXEC SQL CLOSE CC END-EXEC
Example For A Db2 Application Program
IDENTIFICATION DIVISION.
******************************************************************
* IDENTIFICATION DIVISION.
*
*
*
******************************************************************
PROGRAM-ID. SXD11018.
******************************************************************
*
*
******************************************************************
ENVIRONMENT DIVISION.
******************************************************************
*
*
* ENVIRONMENT DIVISION.
*
*
*
******************************************************************
CONFIGURATION SECTION.
******************************************************************
*
* CONFIGURATION SECTION.
*
*
*
******************************************************************
SPECIAL-NAMES.
DECIMAL-POINT COMMA.
INPUT-OUTPUT SECTION.
******************************************************************
*
*
* INPUT-OUTPUT SECTION.
*
*
*
******************************************************************
FILE-CONTROL.
DATA DIVISION.
******************************************************************
*
*
* DATA DIVISION.
*
*
*
******************************************************************
FILE SECTION.
******************************************************************
*
*
* FILE SECTION.
*
*
***********************************************************
WORKING-STORAGE SECTION.
******************************************************************
*
*
* WORKING-STORAGE SECTION.
*
*
*
******************************************************************
*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-**
*
DB2-COMMUNICATION-AREA DECLARATIONS
*
*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*EXEC SQL INCLUDE SQLCA
END-EXEC.
*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-**
*
SQL-TABLE DECLARATIONEN
*
*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*EXEC SQL INCLUDE VT11018
( OUTPUT OF DCLGEN
)
END-EXEC.
/
………………………………………………………………
………………………………………………………………( WORKING STORAGE
VARIABLES )
………………………………………………………………
LINKAGE SECTION.
******************************************************************
* LINKAGE SECTION
*
******************************************************************
*
………………………………………………………………….
…………………………………………………………………
…………………………………………………………
*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-**
*
SQL-CURSOR DECLARATIONS
*
*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*EXEC SQL
DECLARE T11018_ALL_ROW CURSOR FOR
SELECT
TAB_INDEX
, DAHWV
, DAHWB
, DART
FROM
VT11018
ORDER BY TAB_INDEX
END-EXEC.
PROCEDURE DIVISION
******************************************************************
*
*
* PROCEDURE DIVISION
*
*
*
******************************************************************
*
******************************************************************
******************************************************************
*
……………………………………………………….
……………………………………………………….
………………………………………………………
/
******************************************************************
8100-OPEN-T11018-CURSOR SECTION.
******************************************************************
EXEC SQL
OPEN T11018_ALL_ROW
END-EXEC
******************************************************************
…………………………………………………………….
…………………………………………………………….
……………………………………………………………..
………………………………………………………………
8100-FETCH-T11018-ROW SECTION. ( THIS SECTION SHOULD BE IN A
LOOP TO FETCH ALL ROWS)
******************************************************************
EXEC SQL
FETCH T11018_ALL_ROW
INTO
:TAB-INDEX
, :DAHWV
, :DAHWB
, :DART
END-EXEC
******************************************************************
………………………………………………………….
……………………………………………………………
…………………………………………………………………
…………………………………………………………….
8100-CLOSE-T11018-CURSOR SECTION.
******************************************************************
EXEC SQL
CLOSE T11018_ALL_ROW
END-EXEC
STOP RUN.
7.
Program Preparation
This chapter explains the steps involved in executing a db2 application program.
Control information required for each step and examples are also provided
The topics discussed in this chapter are
7.1.
Steps In Program Preparation
7.2.
DCLgen (Declarations Generator )
7.3.
Precompile
7.4.
Bind
7.4.1. Binding A DBRM To A Package
7.4.2. Binding An Application Plan
7.5.
Compile And Linkedit
7.6.
Overview Of DB2 Application Program Preparation And Execution
7.7.
Associating Load Modules And Packages
PROGRAM PREPARATION
STEPS IN PROGRAM PREPARATION
DCLGEN
PROGRAM PRE COMPILE
BIND
COMPILE AND LINK EDIT
EXECUTION
DB2 APPLICATION PROGRAM SHOULD GO THROUGH ALL THE ABOVE
STEPS.
DCLGEN (DECLARATIONS GENERATOR )
INPUT
OUTPUT
DECLARE TABLE
STATEMENT
CONTROL STATEMENTS
WHICH INCLUDE TABLE OR
VIEW NAME AND NAME OF
THE HOST LANGUAGE
DCLGEN
HOST LANGUAGE
DATA STRUCTURE
DCLGEN USES DB2
CATALOG TABLES
 DCLGEN SHOULD BE DONE BEFORE PRE COMPILING THE SOURCE
MODULE
 DCLGEN GENERATES BOTH DECLARE TABLE STATEMENT AND
DATA STRUCTURE IN THE SPECIFIED HOST LANGUAGE.
 DECLARE TABLE STATEMENT USED FOR APPLICATION PROGRAM
DOCUMENTATION AND PRELIMINARY SYNTAX CHECKING FOR THE
PRE COMPILER
 USE DCLGEN OR CODE DECLARE TABLE AND HOST LANGUAGE
DATA STRUCTURE MANUALLY
DCLGEN (Declarations Generator )
The DECLARATIONS GENERATOR supplied with DB2 produces DECLARE
TABLE statements for tables and views. It also generates host language data
structure that corresponds to the DB2 tables and views to be accessed by the
program. The output of DCLGEN will be created in a partition dataset member
This member should be included in the working storage section of the application
program using INCLUDE statement.
The purpose of having DECLARE TABLE statement in the source code is to allow
the pre compiler to check the syntax of the SQL statements referring to the tables
and views. Having the table and view declarations in the source code allows the
pre compiler to uncover syntactical errors, which otherwise would not be found
until DB2 binds the plan or package.
Host language data structure produced by DCLGEN, is the HOST LANGUAGE
DECLARATIONS of tables or views. These can be used as host variables in the
application program. DCLGEN prevents us from manually coding host variable
declarations and declare table statements.
EXAMPLE
INPUT FOR DCLGEN
DCLGEN TABLE(S)
LIBRARY(NTCI.PTAB.DCL(S))
ACTION(REPLACE)
LANGUAGE(COBOL)
STRUCTURE(S)
QUOTE
OUT PUT FROM DCLGEN IN NTCI.PTAB.DCL(S)
******************************************************************
*
DCLGEN TABLE(S)
*
*
LIBRARY(NTCI.PTAB.DCL(S))
*
*
ACTION(REPLACE)
*
*
LANGUAGE(COBOL)
*
*
STRUCTURE(S)
*
*
QUOTE
*
*
IS THE DCLGEN COMMAND THAT MADE THE FOLLOWING
*
STATEMENTS
*
******************************************************************
EXEC SQL DECLARE S TABLE
(S#
CHAR(5) NOT NULL,
SNAME
CHAR(20),NOT NULL WITH DEFAULT
STATUS
SMALLINT NOT NULL WITH DEFAULT,
CITY
CHAR(15) NOT NULL WITH DEFAULT
) END-EXEC
******************************************************************
* COBOL DECLARATION FOR TABLE VT11010
*
******************************************************************
01
S.
10 S#
PIC X(5).
10 SNAME
PIC X(20).
10 STATUS
PIC S9(4) COMP.
10 CITY
PIC X(15).
******************************************************************
* THE NUMBER OF COLUMNS DESCRIBED BY THIS DECLARATION IS 4*
******************************************************************
PRECOMPILE
SOURCE MODULE
SOURCE LISTING
DIAGNOSTICS
CROSS REFERENCES
PRE COMPILE
MODIFIED
SOURCE CODE
(CONTAINS
CONSISTENCY
TOKEN)
DBRM
(CONTAINS
CONTOKEN )
 PRE COMPILER INPUT
HOST LANGUAGE PROGRAM WHICH CONTAINS SQL STATEMENTS
 SQL STATEMENTS ARE COMMENTED OUT ARE REPLACED BY HOST
LANGUAGE CALL STATEMENTS
 PRE COMPILER OUTPUT
 MODIFIED SOURCE CODE WHICH CONTAINS PRE COMPILER
CONSISTENCY TOKEN (CONTOKEN) WHICH IS AN INTERNAL
REPRESENTATION OF TIMESTAMP.

DATABASE REQUEST MODULE WHICH CONTAINS EDITED
FORM OF SQL STATEMENTS AND CONSISTENCY TOKEN

ERROR MESSAGES AND OTHER DIAGNOSTIC INFORMATION
Pre Compile
DB2 application programs include SQL statements and you cannot compile those
programs until you change the SQL statements into the language recognized by
your compiler. Hence you must use a pre compiler whose function is to analyze
the host language source module, stripping all SQL statements it finds and
replacing them by host language call statements. PRE COMPILER also creates a
DBRM from the SQL statements it encountered. DBRM communicates your SQL
requests to DB2 during BIND process.
One DBRM is created for a program, the name of the DBRM and program will be
the same. DBRM contains SQL statements and host variable information
extracted from the source program. The DBRM also contains a consistency token
that identifies the program and ties the DBRM to the modified source statements
by using the same consistency token present in the modified source code.
The pre compiler does a syntax checking using the definition given by the
DECLARE TABLE statement on all SQL statements in the program. Pre compiler
gives error , warnings and other diagnostic messages depending on the result of
syntax checking .
BIND
DBRMS DIRECTLY BOUND TO THE PLAN
INPUT
OUTPUT
DBRM1
BIND
PLAN
DBRM2
DBRMS BOUND TO THE PACKAGE AND PACKAGES BOUND TO THE PLAN
DBRM1
BIND
PACKAGE1
BIND
DBRM2
BIND
PACKAGE2
 THERE ARE TWO TYPES OF BIND
 BIND PACKAGE
 BIND PLAN
PLAN
BIND
 BIND CONVERTS HIGH LEVEL SQL STATEMENTS PRESENT IN DBRM
TO EXECUTABLE MACHINE INSTRUCTION
 BIND THE DBRM TO A PLAN OR PACKAGE BEFORE EXECUTING THE
APPLICATION PROGRAM.
 BIND INVOLVES

CHECKING THE STATUS OF THE REFERENCED OBJECTS TO
DETERMINE IF AN SQL STATEMENT IS EXECUTABLE

CREATING AN OPTIMIZED FORM OF THE SQL STATEMENTS
FOR IMPROVED PERFORMANCE AND COMPACTNESS

IDENTIFYING MOST EFFICIENT PATH FOR EACH SQL
STATEMENT

BIND CHECKS THE AUTHORIZATION TO PERFORM OPERATIONS
REQUESTED BY THE SQL STATEMENT
 THE CONSISTENCY TOKEN PRESENT IN THE DBRM WILL BE CARRIED
FORWARD TO PACKAGE AND PLAN
Bind
The out put of the precompiler contains extracted SQL statements from the
source module. But DB2 has to do the syntax checking and should determine the
best access strategy for each SQL. DB2 records all these information in the
PACKAGE.
If a DBRM is thought of as an ‘SQL source module’ then the package produced
by binding that DBRM can be thought of as the corresponding object module. In
other words, a package consists of a set of internal control structures ,
representing the compiled form of the original SQL statements in the
corresponding DBRM
Each package is assigned to exactly one collection when it is bound. When you
bind a package, you specify the collection to which the package belongs. The
collection is not a physical entity, and you do not create it; the collection name is
merely a convenient way of referring to a group of packages. Usually all of the
packages used in a given application would be assigned to the same collection
There are two types of bind. First method is to bind DBRMS to an application
plan. In the second method DBRMS are bound to the package and packages to
the PLAN. Plan contains pointers to the packages.
Bind examines the SQL statements in the input DBRM an checks whether all the
necessary elements of a statement are present and syntactically correct. It also
checks that the individual binding the plan is authorized to perform the operations
requested by the SQL statement.
Optimizer component of bind interrogates catalog tables, chooses the access
path and generates the machine code calls needed to execute the statement.
BINDING A DBRM TO A PACKAGE
DBRM
CATALOG
PACKAGE BIND
LISTING
DIAGNOSTICS
PACKAGE
 EACH PACKAGE CONTAINS ONLY ONE DBRM.
 PACKAGES ARE OPTIONAL, ALL MEMBERS CAN BE DIRECTLY BOUND
TO A SINGLE PLAN
 INPUT TO THE PACKAGE BIND IS DBRM AND OUTPUT IS THE PACKAGE.
 PACKAGE MUST BE BOUND TO THE PLAN
 CON-TOK FROM THE DBRM WILL BE CARRIED ON TO PACKAGE
Binding A DBRM To A Package
Bind Package Is Explained Using The Following Example
BIND PACKAGE
MEMBER
OWNER
QUALIFIER
VALIDATE
EXPLAIN
ISOLATION
RELEASE
ACTION
(EWSK)
(SXD11010)
(AM1240)
(SYSADMK )
(BIND)
(NO)
(CS)
(COMMIT)
(REPLACE)
-
When you BIND a package specify the collection to which the package belongs.
The collection is not a physical entity and you do not create it.
In the example collection name is EWSK and the package name produced by this
bind is EWSK.SXD11010
The owner of the package is AM1240.The owner of an object has all privileges on
that object. If no value is entered the default is the use of the primary AUTHID of
the binder.
The qualifier parameter will be used as the qualifier of all unqualified tables and
views referenced in the application program.
Validate parameter is used to specify the method DB2 will use to validate the
package or plan. Validation can be performed during bind or when the program
runs, indicated by the choices of BIND or RUN with the VALIDATE parameter.
VALIDATE (RUN) is the default value.
EXPLAIN indicates whether to provide information to the user about the access
strategy decided by the bind. Default is EXPLAIN(NO)
ACTION parameter indicates whether the package is new or a replacement.
ACTION (ADD) will result in an error if the object already exists. The default value
of REPLACE will add the object or replace it if it already exists.
ISOLATION specifies the locking strategy while using cursors. Default is RR
(repeatable read) , can be over ridden using CS (cursor stability): For more
information on ISOLATION parameter please refer chapter 9
RELEASE parameter indicates when the locks should be released while using a
cursor.
BINDING AN APPLICATION PLAN
LIST OF PACKAGES
OR
DBRMS
OR
BOTH
PLAN BIND
LISTING
DIGNOSTIC
MESSAGES
PLAN
 DBRMS CAN BE BOUND TO A PLAN
 A LIST OF PACKAGES CAN BE BOUND TO A PLAN
 DBRMS AND PACKAGES TOGETHER CAN BE BOUND TO A SINGLE
APPLICATION PLAN
 PLAN CONTAINS POINTERS TO THE PACKAGES
Binding An Application Plan
BIND PLAN IS EXPLAINED USING THE FOLLOWING EXAMPLE
BIND PLAN (A610 )
MEMBER(W41600, w710009)
OWNER(SYSADM)
QUALIFIER(SYSADM)
PKLIST(EWS.A61000
EWS.SXD11053 ,
EWSA.ANLZDB2)
ACTION(REPL) RETAIN
VALIDATE(BIND)
ISOLATION(CS)
CACHESIZE(0)
-
In the above example name of the plan is A610, two DBRMS, and three packages
are bound to the plan.
Parameters used in this example have the same meaning as in the bind package
statement.
The parameter ACTION indicates whether a new package is to be added or
replaced. ACTION(REPL)RETAIN can be used only for BIND PLAN. RETAIN
parameter preserves EXECUTE privileges when you replace the plan. If RETAIN
is specified then those users who had been using the plan earlier will have the
authority to use it after the bind.
Determines the size (in bytes) of the authorization cache acquired in the EDM
pool for the plan. At run time, the authorization cache stores user IDs authorized
to run. Consulting the cache can avoid a catalog lookup for checking authorization
to run the plan.
COMPILE AND LINKEDIT
MODIFIED
SOURCE MODULE
(CONTAINS CONTOKEN)
COMPILER
OBJECT MODULE
LINK EDITOR
OTHER
OBJECT MODULES
LOAD MODULE
(CONTAINS CONTOKEN)
 MODIFIED SOURCE FROM THE PRE COMPILER IS COMPILED USING
HOST LANGUAGE COMPILER WHICH PRODUCES OBJECT MODULE.
 LINKAGE EDITOR IS USED TO MAKE AN EXECUTABLE LOAD MODULE
WHICH CONTAINS MAIN PROGRAM, SUB PROGRAMS, LANGUAGE
INTERFACE ROUTINES, AND SYSTEM ROUTINES.
 TIMESTAMP PRESENT IN THE MODIFIED SOURCE IS CARRIED ON TO
THE LOAD MODULE
OVERVIEW OF DB2 APPLICATION PROGRAM
PREPARATION AND EXECUTION
SOURCE
MODULE
MODIFIED
SOURCE
MODULE
PRECOMPILER
DBRM
COMPILER
BIND
OBJECT
MODULE
PACKAGE
LINKAGE
EDITOR
LOAD
MODULE
OTHER
OBJECT
MODULES
LIST OF
PACKAGES
LOAD MODULE
PLAN / PACKAGES
MAIN MEMORY
BIND
APPLICATION
PLAN
ASSOCIATING LOAD MODULES AND PACKAGES
CT
CT
PRE COMPILE
MODIFIED
SOURCE
DBRM
CT
CT
LOAD
MODULE
PLAN
CONTOKENS
SHOULD MATCH
TO EXECUTE
Associating Load Modules And Packages
During PRECOMPILE a CONSISTENCY TOKEN is placed in both the modified
source and the DBRM. When DBRM is directly bound to the plan then the
CONSISTENCY TOKEN is carried on to the plan from the DBRM. When DBRM is
bound to the package then the same CONSISTENCY TOKEN will be present in
the package and plan contains pointers to the package. An executable load
module can be linked to it’s plan or package using the CONSISTENCY TOKEN
field present in them. CONSISTENCY TOKEN is used to ensure that the resultant
load module and package were derived from the same original source.
Assume that the plan of an application program contains only DBRMS. When this
program executes the CONSISTENCY TOKEN present in the load module and
the corresponding DBRM should be the same . Otherwise the program will not be
executed and gives an SQLCOSE OF -805.
Now the DBRM of an application program is bound to the package and a set of
packages are bound to the plan. When this program is executed the load module
and the package which the program wants to execute should have the same
CONSISTENCY TOKEN, failure of this will give an SQLCODE -805.
8.
Security Features
DB2 provides data integrity by using different security mechanisms. Data access
is controlled by using authorization ID’s and privileges given to that ID. This
chapter briefly explains these security features and DB2’s referential integrity
support.
8.1.
Privileges
8.2.
Referential Integrity
8.2.1. DB2 Enforcement Of Referential Integrity
8.2.2. Referential Integrity Enforcement Rules
8.2.3. Example For Referential Integrity Violation
8.3.
Database Recovery In Case Of Failure
8.3.1. Unit Of Recovery
8.3.2. Data Recovery
SECURITY FEATURES
 SECURITY IN DATABASE MEANS THE PROTECTION OF ALL OBJECTS
IN DATABASE AGAINST UNAUTHORIZED DISCLOSURE, ALTERATION
OR DESTRUCTION.
 DB2 USES TWO INDEPENDENT FEATURES TO PROVIDE SECURITY TO
IT’S OBJECTS


THE AUTHORIZATION SUB SYSTEM
THE VIEW MECHANISM
 THE SYSTEM ADMINISTRATOR PROVIDES AUTHORIZATION ID’S TO
IT’S USERS. THIS ID IS USED TO LOG ON TO THE SYSTEM AND THE
ACTIVITIES USER CAN PERFORM IN DB2 DEPENDS ON THE
PRIVILEGES GRANTED TO THIS ID.
 THERE ARE TWO TYPES OF AUTHORIZATION ID’S


PRIMARY AUTHORIZATIONS IDS
SECONDARY AUTHORIZATION IDS
 VIEW MECHANISM CAN BE USED TO PROTECT SENSITIVE DATA FROM
USERS BY CREATING A VIEW ON COLUMNS OF THE BASE TABLE
THAT ARE NOT SENSITIVE. NOW THE USER ARE ALLOWED TO USE
THIS VIEW , PROTECTING SENSITIVE DATA.
Security Features
Authorization ID’S are provided to users of DB2 to prevent unauthorized use of
DB2 objects. Users are known to DB2 by this authorization identifier given by the
system administrator and it is user’s responsibility to identify themselves to by
supplying that ID when they sign on to the system.
Two types of authorization ID’s DB2 uses to control and track system utilization
are primary and secondary AUTHIDs.
Each individual is assigned a PRIMARY AUTHID that is used to sign on to the
system. Generally it is the primary authorization ID that identifies a process in
DB2. When unqualified tables, views, indexes are used in the application
program, this AUTHID becomes the qualifier of the object. The operations which
can be performed by this AUTHID depends on the privileges granted to it by
system administrator or other users.
System administrator may provide a secondary authid to a group of developers
who need a set of privileges associated with that id. Now the user has all the
privileges of both primary and secondary authid. The secondary authorization ID
is optional .
A user can use DB2 under either a primary AUTHID or secondary AUTHID or
both. Suppose you are using primary id and want to shift to secondary authid for
some operation to perform . This shift can be achieved by using the command
SET CURRENT SQLID = ‘ (name of secondary id)’.
PRIVILEGES
 SYSTEM ADMINISTRATOR DECIDES WHICH SPECIFIC PRIVILEGE
SHOULD BE GIVEN TO WHICH SPECIFIC USERS
 DATABASE ADMINISTRATOR HAS IMPLICIT RIGHT TO GRANT OR
REVOKE PRIVILEGES FROM THE USER.
 DATABASE ADMINISTRATOR CAN GIVE INDIVIDUAL OR A COLLECTION
OF PRIVILEGES TO USERS
 CREATOR OF AN OBJECT HAS IMPLICIT RIGHT TO DROP OR ALTER
THE OBJECT

SYSTEM ADMINISTRATOR HAS THE AUTHORITY TO TAKE ANY
POSSIBLE ACTION WITHIN THE DB2 SYSTEM.

PRIVILEGES ARE GIVEN AND TAKEN BACK USING GRANT AND
REVOKE COMMANDS
Privileges
SYSTEM ADMINISTRATOR has the authority on all objects in DB2. In order to
perform any operation in DB2, the user must hold appropriate privilege for the
operation and the object in question, Otherwise the request will be rejected.
System administrator grants single or group (bundled) privileges to users.
Group of privileges (BUNDLED PRIVILEGES) used in DB2 are shown below
SYSADM
SYSTEM ADMINISTRATOR AUTHORITY allows the holder to execute any
operation that the system supports.
SYSCTRL
SYSTEM CONTROL AUTHORITY allows the holder to execute any operation,
except for operation that access database contents.
Example: CREATE STOGROUP
DBADM
DATABASE ADMINISTRATOR AUTHORITY on a specific database allows the
holder to execute any operation that the system supports on the database
Example: SELECT, UPDATE etc
DBCTRL
DATABASE CONTROL AUTHORITY on a specific database allows the holder to
execute any operation that system supports except for data manipulation
operation
Example: RECOVER DATABASE
DBMAINT
DATABASE MAINTENANCE AUTHORITY on a specific database allows the
holder to execute read only maintenance functions on the database
Example: DISPLAY DATABASE, START DATABASE etc
SYSOPR
SYSTEM OPERATOR AUTHORITY allows the holder to carry out console
operator functions on the system.
Example: STARTING AND STOPPING SYSTEM TRACE ACTIVITIES
PACKADM
package administrator authority on a specific collection allows the holder to create
packages in that collection and gives the holder all package privileges in that
collection
REFERENTIAL INTEGRITY
DB2’S REFERENTIAL INTEGRITY SUPPORT
 THERE ARE TWO GENERAL INTEGRITY RULES IN DB2 FOR
MAINTAINING DATA INTEGRITY
ENTITY INTEGRITY RULE
NO COMPONENT OF PRIMARY KEY OF A BASE TABLE IS
ALLOWED TO ACCEPT NULLS.
REFERENTIAL INTEGRITY RULE
REFERENTIAL INTEGRITY RULE STATES THAT ALL NON
NULL VALUES OF FOREIGN KEY MUST APPEAR AS A
VALUE OF THE PRIMARY KEY OF SOME SPECIFIC TABLE

BY DEFINITION FOREIGN KEY IN ONE TABLE MATCHES A PRIMARY
KEY.

A PRIMARY KEY MUST BE UNIQUE AND CANNOT BE NULL

A FOREIGN KEY VALUE MUST MATCH A PRIMARY KEY VALUE OR BE
NULL
DB2’S Referential Integrity Support
Referential integrity consists of a set of rules used in DB2 to provide accuracy ,
validity or correctness of data in database. Maintaining integrity is of paramount
importance and this task is handled by the system rather than the user . For this
the system needs to be aware of integrity rules, it should monitor all operations
and should ensure that they do not violate any of those rules.
DB2 supports ENTITY INTEGRITY RULE by enforcing the programmer to make
the column declaration of the primary key not null. If the primary key is composite
then all the columns in that composite key should be declared as not null. The
justification for this is basically that the primary key values in base tables serve to
identify entities in the real world. Primary keys are used for direct row level
retrieval and relating one table to another in relational database. Therefore an
unknown value in primary column will be meaningless.
DB2 enforces that values of a given foreign key must match the values of the
corresponding primary key. But the converse is not a requirement. ie the primary
key corresponding to some given foreign key might contain a value that currently
does not appear as a value of that foreign key. Table which contains the primary
key is the parent table and table containing foreign key is the dependent table.
This referential integrity rule can be violated during data manipulation like update,
delete, insert. DB2 will monitor all operations and it will not allow any violation in
referential integrity rules.
DB2 ENFORCEMENT OF REFERENTIAL INTEGRITY
 DB2 ENFORCES REFERENTIAL CONSTRAINTS WHEN

AN INSERT STATEMENT IS APPLIED TO THE DEPENDENT
TABLE

AN UPDATE STATEMENT IS APPLIED TO A FOREIGN KEY OF A
DEPENDENT TABLE OR AN UPDATE OF THE PRIMARY KEY OF
THE PARENT TABLE

A DELETE STATEMENT IS APPLIED TO A PARENT TABLE
 AN INSERT INTO A PRIMARY KEY TABLE CANNOT VIOLATE
REFERENTIAL INTEGRITY AND NO CHECKING IS REQUIRED
 DELETION OF A FOREIGN KEY VALUE CANNOT VIOLATE REFERENTIAL
INTEGRITY AND NO CHECKING IS REQUIRED
REFERENTIAL INTEGRITY ENFORCEMENT RULES
 INSERT RULE

THE INSERTION OF ANY FOREIGN KEY VALUE IN THE DEPENDENT
TABLE IS ALLOWED ONLY IF THE MATCHING VALUE EXISTS IN
THE PRIMARY KEY OF THE PARENT TABLE
 UPDATE RULE

CHANGES IN THE PRIMARY KEY VALUES ARE ALLOWED ONLY
FOR THOSE VALUES THAT DO NOT HAVE MATCHING FOREIGN
KEY VALUES

UPDATING A FOREIGN KEY VALUE IS ALLOWED ONLY IF SUCH A
VALUE EXISTS IN THE PRIMARY KEY
 DELETE RULE

DELETION OF A PRIMARY KEY VALUE WHEN A CORRESPONDING
VALUE EXISTS


WILL BE BARRED IF THE FOREIGN KEY CONSTRAINT HAS
BEEN SPECIFIED AS RESTRICT
WILL CAUSE DELETION OF THE CORRESPONDING FOREIGN
KEY VALUES IF THE CONSTRAINT HAS BEEN SPECIFIED AS
CASCADE

WILL SET THE CORRESPONDING FOREIGN KEY VALUES TO
NULL IF THE CONSTRAINT HAS BEEN SPECIFIED SET
NULL
Referential Integrity Enforcement Rules
When integrity constraints are in effect, a few data manipulations like INSERT,
UPDATE, DELETE) hold the potential for integrity violations or for unpredictable
or anomalous results. DB2 detects some of these situations when it attempts to
bind SQL statements that result in problems. Instead of completing such a bind,
DB2 issues an error message.
Insertion of rows containing new primary key values of the parent table do not
require checks of associated foreign keys because additions pose no threat to
referential integrity. Values added to foreign key columns of depended table
through inserts, on the other hand must have corresponding primary key values.
Updating the primary key of the parent table will be restricted if matching foreign
keys are found in dependent table. While updating the dependent table the new
foreign key value must be present in the parent table. Otherwise the request will
be rejected.
The delete rule of a referential constraint applies when a row of the parent table is
deleted. The effect of this delete on dependent tables will dependent on the ON
DELETE clause of FOREIGN KEY DEFINITION. The possible specifications of
ON DELETE clause are RESTRICT, CASCADE, SET NULL.
When the deleting a primary key value, assume that the delete rule is RESTRICT,
then the delete is restricted to the case where there are no matching rows in the
dependent table. If matching rows exist then the delete request will be rejected.
The delete rule CASCADE deletes all matching rows. Ie This deletes the row
corresponding to the primary key in parent table and the matching rows in
dependent table.
For using the delete rule SET NULL the foreign key must have nulls allowed.
Here row corresponding to the primary key value in the parent table will be
deleted and the foreign key value will be set to null in all matching rows of the
primary key in dependent table.
Example For Referential Integrity Violation
TABLE S
S#
S1
S2
S3
S4
S5
TABLE SP
SNAME
SMITH
JONES
BLAKE
CLARK
ADAMS
STATUS
20
10
30
20
30
CITY
S#
P#
LONDON
PARIS
PARIS
LONDON
ATHENS
S1
S1
S1
S1
S1
S1
S2
S2
S3
S4
S4
S4
P1
P2
P3
P4
P5
P6
P1
P2
P2
P2
P4
P5
QTY
300
200
400
200
100
100
300
400
200
200
300
400
Consider tables S and SP for explaining the implications of REFERENTIAL
INTEGRITY concept
PRIMARY KEY; FOREIGN KEY clauses of the create table statements for these
tables are given below
TABLE SP
TABLE S
PRIMARY KEY ( S#, p# )
FOREIGN KEY SFK ( S# )
REFERENCES S
ON DELETE CASCADE
FOREIGN KEY PFK ( P# )
REFERENCES P
ON DELETE RESTRICT
PRIMARY KEY ( S# )
In this example table S is the parent table and table SP is the dependent table.
PFK and SFK are constraint names that will be used by DB2 in diagnostic
messages relating to the foreign keys S# and P#. If the user does not specify the
name DB2 will create one derived from the name of the first column participating
in the foreign key.
Four different cases of potential referential integrity violations for these tables are
explained below
CASE1
An insert on the SP table might introduce a shipment for which there is no
matching supplier. For example
INSERT
INTO SP (S#, P#, QTY )
VALUES ( ‘S20’, ……) ;
CASE2
An update on column SP.S# of the SP table might introduce a shipment supplier
number for which there is no matching supplier. For example
UPDATE SP
SET S# = ‘S20’
WHERE….;
CASE3
A deletion on the S table might remove a supplier for which there exists a
matching shipment. For example
DELETE
FROM S
WHERE S# = ‘S1’ ;
CASE4
An update on column S.S# of the S table might remove a supplier for which there
exists a matching shipment . For example
UPDATE S
SET
S# = ‘S20’
WHERE S# = ‘S1’ ;
In order to enforce referential constraint, the system must deal with all four of
these cases.
Explanation
CASE1
This situation is prevented by the virtue of the fact that SP.S# is a foreign key in
table SP matching the primary key S.S# of table S. Such an insert will simply be
rejected. But an insert that introduces a shipment for a supplier that does already
exist in table S will be accepted.
CASE2
In this case also the update will be rejected . But an update that introduces an
SP.S# value that does already exist in table S will be accepted.
CASE3
This situation is handled by the delete rule CASCADE. In general RESTRICT
would mean that the delete will be accepted only if there no such matching
shipments. CASCADE would mean that any such matching shipments will de
removed anyway. And SET NULL would mean that any such matching shipments
will not be removed but will be updated so that they are no longer matching.
CASE4
This situation is handled by the implicit update rule restrict, which means that the
update will be accepted only If no such matching shipments exist.
DATABASE RECOVERY IN CASE OF FAILURE
UNIT OF RECOVERY
POINT OF
CONSISTENCY
NEW POINT OF
CONSISTENCY
OLD
DATA UPDATES
UPDATED
DATA
UNIT OF RECOVERY
DATA
COMMIT
POINT OF
CONSISTENCY
NEW POINT OF
CONSISTENCY
ABNORMAL
TERMINATION
DATA UPDATES
BACK OUT UPDATES
OLD
OLD
DATA
DATA
 SUCCESSFUL EXECUTION OF MULTIPLE SQL STATEMENTS MAY BE
NECESSARY TO COMPLETE A LOGICAL UNIT OF RECOVERY
 THE APPLICATION PROGRAMMER MUST DETERMINE THE LOGICAL
UNIT OF RECOVERY
 DATABASE RECOVERY
CONSISTENCY
IS
DONE
TO
THE
LAST
POINT
OF
Unit Of Recovery
A unit of recovery is the work done by a DB2 for an application, that changes DB2
data from one point of consistency to another. A point of consistency is a time
when all recoverable data that an application program accesses is consistent with
other data.
A unit of recovery begins with the first change to the data after the beginning of
the job or following the last point of consistency and ends at a later point of
consistency. If failure occurs within a unit of recovery, DB2 backs out any
changes to data, returning the data to its state at the start of the unit of recovery;
that is, DB2 undoes the work.
DATA RECOVERY
BACKUP
DATA BASE
UPDATED
DATABASE
COMMIT
UPDATE1
UPDATE2
F
A
I
L
U
R
E
LOG
BACKUP
RECOVERED
DATABASE
RESTORE
UPDATE
LOG
Data Recovery
Backups are maintained by database administration for the data in DB2
subsystem. Backups may be of the entire database or of one or more
tablespaces. In case of failure database recovery is done using these backups.
All data changes and other significant activities are recorded in logs by DB2.
Database manager may use the backup copies and the logs to re-establish the
data base to the last committed unit of work. Changes that were not committed
before the failure are not recovered in any case
In the given example, the backup is made for a database by DB2. After that the
database is changed , and that is made permanent by issuing a commit. Again
the application program tries to do another update and before it’s completion a
failure occurs
Now we want to recover the data in the database. The database is recovered
from he backup and the changes that were made in that database till the last
commit were done. and the database is restored.
9.
Concurrency
Objects in DB2 can be used by many users at the same time. This is achieved by
the using proper locking system. This chapter explains how DB2 uses these locks
and how much control the programmer has over the concurrency in DB2.
9.1.
Concurrency
9.2.
Locking Strategy
9.3.
Lock Sizes And Types
9.4.
Acquire Release Parameters
9.5.
Isolation Parameter
CONCURRENCY
 DB2 ALLOWS ANY NUMBER OF USERS TO ACCESS THE SAME TABLE
AT THE SAME TIME .THIS IS CALLED CONCURRENCY
 DB2 USES A CONCURRENCY CONTROL MECHANISM TO AVOID
ERRORS AND INCONSISTENCIES IN DATA WHEN MULTIPLE USERS
ACCESS THE SAME DATABASE.
 DB2 MANAGES CONCURRENCY CONTROL WITH SEVERAL TYPES OF
LOCKS THAT RESTRICT ACCESS TO DATA WHILE THEY ARE BEING
USED
 CONCURRENCY CONTROL ELIMINATES THE POSSIBILITY OF ONE
USER CHANGING DATA WHILE ANOTHER IS IN THE PROCESS OF
USING OR CHANGING THEM WHICH CAN LEAD TO ERRORS OR
INCONSISTENCIES IN DATA.
Concurrency
DB2 is a shared system, that is a system that allows any number of users to
access the same database at the same time. Any such system requires some
kind of concurrency control mechanism to ensure that concurrent transactions do
not interfere with each other operation. The absence of such a mechanism will
lead to errors and inconsistencies in data
DB2 uses locks to control access to same database by multiple users. The basic
idea of locking is simple, when a transaction needs an assurance that some
object that is interested in, will not change in some unpredictable manner by
another user. An exclusive lock on the object will provide this assurance. The
effect of the lock is to lock other transactions out of the object, and thereby to
prevent them from changing it. The first transaction is thus able to carry out its
processing in the certain knowledge that the object in question will remain in a
stable state for as long as the transaction wishes to.
If a transaction requests a lock that is not currently available, then the transaction
simply waits until it gets it. In practice the installation can specify a maximum wait
time; If a transaction ever reaches that threshold in waiting for a lock, it times out
and the lock request is failed.
LOCKING STRATEGY
 DB2 DETERMINES IT’S LOCKING STRATEGY FOR EACH PROGRAM
WHEN IT BINDS THE APPLICATION PLAN. THE LOCKING STRATEGY
DEPENDS ON SEVERAL FACTORS

THE LOCK SIZES DECLARED IN THE LOCKSIZE PARAMETER
OF CREATE TABLESPACE STATEMENT

TYPE OF SQL STATEMENTS

THE PRESENCE OF EXPLICIT LOCK TABLE STATEMENTS

THE ACQUIRE AND RELEASE OPTIONS CHOSEN BY THE
DEVELOPER AT BIND TIME

THE ISOLATION LEVEL CHOSEN AT BIND TIME.

THE ACCESS PATH CHOSEN
Locking Strategy
DB2 allows multiple users to access same object at same time, but they are
controlled by locks. DB2 selects appropriate locking mechanism based on
concurrency control requirements inherent in the application program. They are
called implicit locks.
In addition to the implicit locking mechanism, DB2 provides certain explicit
facilities.
These explicit facilities are
1.
2.
3.
4.
LOCKSIZE parameter of CREATE TABLESPACE statement.
ISOLATION parameter
ACQUIRE / RELEASE parameter
SQL statement LOCKTABLE.
Lock table statement can be coded in the application program to acquire an
explicit lock on an object on behalf of the application program. Other parameters
are explained in the following pages.
Example
LOCK TABLE SP IN EXCLUSIVE MODE;
LOCK SIZES AND TYPES
 THE SIZE (SCOPE) OF A LOCK ON DATA IN A TABLE DESCRIBES THE
AMOUNT OF DATA CONTROLLED
 THE SIZE IS SPECIFIED IN THE LOCKSIZE PARAMETER OF CREATE
TABLESPACE STATEMENT

LOCKSIZE TABLESPACE
THIS MEANS THAT ALL LOCKS ACQUIRED ON DATA IN THE
TABLE SPACE WILL BE AT THE TABLE SPACE LEVEL

LOCK SIZE TABLE
THIS MEANS THAT LOCKS ACQUIRED ON DATA IN THE TABLE
SPACE WILL BE AT THE TABLE LEVEL

LOCKSIZE PAGE
THIS MEANS THAT LOCKS ACQUIRED ON DATA IN THE TABLE
SPACE WILL BE AT TABLE LEVEL

LOCKSIZE ROW
THIS MEANS THAT THE LOCKS ACQUIRED ON DATA IN THE
TABLE SPACE WILL BE AT THE ROW LEVEL

LOCKSIZE ANY
THIS MEANS THAT DB2 WILL DECIDE THE APPROPRIATE
PHYSICAL UNIT OF LOCKING FOR THE TABLESPACE
 DB2 ALWAYS REQUIRES A TABLE OR TABLESPACE LOCK BEFORE
ACCESS TO DATA IS PERMITTED .
 DB2 MAY USE TABLE OR TABLESPACE LOCK ALONE TO ACCESS
DATA ACCORDING TO THE LOCKSIZE PARAMETER
 IF THE LOCKING STRATEGY INCLUDES ROW OR PAGE LOCKING THEN
DB2 LOCKS TABLE OR TABLE SPACE BEFORE LOCKING ROW OR
PAGE
Lock Sizes And Types
Proper selection of lock size is important for better performance and concurrency
of the database. A locksize of tablespace allows a process to lock the tablespace
which controls all tables inside the table space. On the other hand row lock will
only lock the row which the application program wants.
In a simple tablespace locking table space means locking all tables inside that
table space which will reduce concurrency. But a page lock will lock only those
rows of tables present in that page and other users can access other rows in that
tablespace concurrently.
Locking larger or smaller amounts of data allows you to trade performance for
concurrency. When you use page or row locks instead of table or tablespace
locks concurrency usually improves, meaning better response times .When you
use only table or tablespace locks then processing time and storage used is
reduced. But concurrency is also reduced , meaning longer response times for
some users.
For maximum concurrency, locks on a small amount of data held for a short
duration are better than locks on a large amount of data held for a long duration
of time. However acquiring a lock requires processor time, and holding a lock
requires storage. These things should be kept in mind while deciding a lock size.
ACQUIRE RELEASE PARAMETERS
 ACQUIRE AND RELEASE ARE BIND OPTIONS WHICH WILL DETERMINE
WHEN TO ACQUIRE AND RELEASE ITS LOCKS
 ACQUIRE ( ALLOCATE )
ACQUIRES THE LOCK WHEN THE PLAN IS ALLOCATED
 ACQUIRE (USE )
ACQUIRES THE LOCK WHEN THE OBJECT IS FIRST ACCESSED.
 RELEASE (DEALLOCATE)
RELEASES THE LOCKS WHEN THE PLAN IS DE ALLOCATED
 RELEASE(COMMIT)
RELEASES THE LOCK AT THE NEXT COMMIT POINT. IF THE
APPLICATION ACCESSES THE OBJECT AGAIN IT MUST ACQUIRE
THE LOCK AGAIN
ISOLATION PARAMETER
 ISOLATION PARAMETER SPECIFIES THE LOCKING STRATEGY
FOR CURSORS
 THE ISOLATION LEVEL CHOSEN FOR AN APPLICATION CAN
IMPACT BOTH THE LOCK STRATEGY AND THE DURATION OF
ROW LOCKS
 THE ISOLATION LEVEL CAN BE SPECIFIED DURING BIND TIME
 DIFFERENT ISOLATION LEVELS ARE




REPEATABLE READ(RR)
READ STABILITY(RS)
CURSOR STABILITY(CS)
UNCOMMITTED READ(UR)
 DEFAULT VALUE FOR ISOLATION PARAMETER IS REPEATABLE
READ(RR)
 ISOLATION SPECIFIES THE DEGREE TO WHICH OPERATIONS ARE
ISOLATED FROM THE POSSIBLE EFFECTS OF OTHER OPERATIONS
ACTING CONCURRENTLY.
 BASED ON THIS INFORMATION, DB2 CHOOSES TABLE AND TABLE
SPACE LOCKS AS NONRESTRICTIVE AS POSSIBLE, AND RELEASES S
AND U LOCKS ON ROWS OR PAGES AS SOON AS POSSIBLE.
Isolation parameter
If an SQL statement embedded in a host language program will return multiple
rows, the developer must declare in the program a cursor that presents them to
the host program one at a time, usually with in a repeatedly executed block. DB2
can handle locking for these cursors using different ISOLATION levels.
ISOLATION(RR)
Repeatable read: A row or page lock is held for all accessed
rows, qualifying or not, at least until the next commit point. If the application
process returns to the same page and reads the same row again, the data cannot
have changed and no new rows can have been inserted.
ISOLATION (RS) Read stability: A row or page lock is held for pages or rows
that are returned to an application at least until the next commit point. If a row or
page is rejected during stage 2 processing, its lock is still held, even though it is
not returned to the application.
If the application process returns to the same page and reads the same row
again, the data cannot have changed, although additional rows might have been
inserted by another application process. A similar situation can also occur if a row
or page that is not returned to the application is updated by another application
process. If the row now satisfies the search condition, it appears.
ISOLATION(CS)
Cursor stability: A row or page lock is held only long enough
to allow the cursor to move to another row or page. For data that satisfies the
search condition of the application, the lock is held until the application locks the
next row or page. For data that does not satisfy the search condition the lock is
immediately released.
ISOLATION(UR)
Uncommitted read: The application acquires few locks and
can run concurrently with most other operations. But the application is in danger
of reading data that was changed by another operation but not yet committed.
10.
DB2I (DB2 Interactive )
DB2I is an interactive facility available in DB2 . Almost all of the functions of DB2
are available in DB2I , Which can be used by developers .This chapter contains
10.1. DB2I
10.2. SPUFI
DB2I (DB2 INTERACTIVE )
 THE DB2 INTERACTIVE INTERFACE IS A TSO ONLINE APPLICATION
WHICH WORKS UNDER THE CONTROL OF ISPF(INTERACTIVE SYSTEM
PRODUCTIVITY FACILITY) WHICH IS A SCREEN /DIALOG MANAGER
FOR TSO
 DB2I PROVIDES OPTIONS FOR ALL THE DB2 FUNCTIONS THAT
DEVELOPERS ARE LIKELY TO NEED
 DB2 FUNCTIONS THAT ARE AVAILABLE THROUGH DB2I ARE SHOWN
IN THE DB2PRIMARY OPTION MENU
DB2 PRIMARY OPTION MENU
===>
select one of the following db2 functions and press enter
1 SPUFI
2 DCLGEN
3 PROGRAM PREPARATION
4 PRE COMPILE
5 BIND/REBIND/FREE
6 RUN
7 DB2 COMMANDS
8 UTILITIES
9 CATALOG VISIBILITY
d DB2I DEFAULTS
x EXIT
(Process SQL statements)
(Generate SQL and sorce language
declarations)
(Prepare a DB2 application program
to run)
(Invoke DB2 pre compiler)
(Bind rebind or free appl. Plans or
packages)
(RUN an SQL program)
(Issue DB2 commands)
(Invoke DB2 utilities)
(Invoke catalog dialogs)
(set global parameters)
( leave DB2)
DB2I
DB2 provides a number of commands for use in readying a program for execution
that programmers can use to perform the functions required to convert code from
source to executable modules. A convenient alternative is to work through DB2I ,
which provides a menu interface to the necessary command processor . If you
develop programs using TSO and ISPF, you can prepare them to run using the
DB2 Program Preparation panels. These panels guide you step by step through
the process of preparing your application to run. There are other ways to prepare
a program to run, but using DB2I is the easiest, as it leads you automatically from
task to task.
DB2I primary option menu lists the functions it can perform. The user can select
any one of these functions according to his requirements
SPUFI (SQL processor using file input) supports the online execution SQL
statements from a TSO terminal. SPUFI is intended basically for application
programmers who wish to perform SQL portions of their programs.
The DCLGEN menu allows users to invoke the declarations generator program,
which produces the DECLARE TABLE statements and host language data
structure.
Other options like PRECOMPILE, BIND, RUN are used for preparing and
executing DB2 application program.
UTILITIES menu helps the user to invoke DB2 online utilities like LOAD, REORG,
RECOVER etc. The necessary utility control statements to direct the operation of
the specific utility must be created before the utility is invoked.
SPUFI
INPUT SQL
STATEMENTS
SPUFI
OUTPUT
RESULTS
DB2
 SPUFI PROCESSES INCLUDE

PREPARING INPUT FILE FOR SPUFI

DB2I SUBMITS THE SQL TO DB2

SUCCESSFUL JOBS ARE AUTOMATICALLY COMMITTED

EXAMINING THE RESULTS OF SQL
11.
Utilities
For analyzing and managing physical data present in data base, DB2 offers a
number of utilities . This chapter gives a brief explanation of these utilities
11.1. Load
11.2. Runstats
11.3. Reorg
UTILITIES
DB2 OFFERS A NUMBER OF UTILITIES FOR ANALYZING
AND MANAGING THE PHYSICAL STORAGE OF DATA .
THERE ARE TWO TYPES OF DB2 UTILITIES.
ONLINE UTILITIES
STAND ALONE UTILITIES
 DB2 ONLINE UTILITIES RUN AS STANDARD MVS BATCH
JOBS, AND THEY REQUIRE DB2 TO BE RUNNING
 THE STAND-ALONE UTILITIES EXECUTE AS BATCH JOBS
INDEPENDENT OF DB2. THEY CAN BE INVOKED ONLY BY
MEANS OF MVS JCL.
IMPORTANT ONLINE UTILITIES ARE




LOAD
REORG
RECOVER
RUNSTATS
IMPORTANT STAND ALONE UTILITIES ARE
 DSNJU003
 DSNJU004
 DSN1CHKR
LOAD
THE LOAD UTILITY LOADS DATA FROM A SEQUENTIAL
FILE TO ONE OR MORE TABLES IN A TABLESPACE
INPUT
DATA
LOAD UTILITY
CORRECT DATA DB2 TABLE
EXAMPLE
CONTROL INFORMATION FOR LOAD UTILITY
LOAD DATA
RESUME NO
LOG NO
inddn ddname
INTO TABLE D2110K.S
( S# POSITION (1)
P# POSITION (6:11)
QTY POSITION (12:15)
CHAR 5
CHAR 6
INTEGER );
Load
Load utility is used to load data from a sequential file to a TABLE in a table space.
In the previous example the TABLE S is loaded from the dataset specified in the
load jcl. ddname of the input dataset that is used in the LOAD JCL is given in
INDDN parameter. Each fields and their positions are also specified.
If the table space already contains data, you can choose whether you want to add
new data to existing data or replace the existing data. This can be done using the
parameter RESUME.
There are three options for RESUME.
RESUME NO: Indicates that the dataset is to be empty. This is the default option.
RESUME NO REPLACE: This causes the utility to over write the existing data.
RESUME YES: This allows the utility to add new rows to the existing table.
The LOG NO command instructs the utility not to record data in the log as they
are loaded .IF the user does not specify LOG NO , the utility records the changes
which can be used for recovery purpose. Default is LOG YES. Recording data in
the log during a load can increase the time required for the load significantly.
RUNSTATS
RUNSTATS UTILITY COLLECTS STATISTICS OF TABLESPACE
AND UPDATES CATALOG TABLES
RUNSTATS SHOULD BE EXECUTED IMMEDIATELY AFTER A
TABLE AND IT’S INDEXES ARE CREATED AND THE DATA IS LOADED
DB2 OPTIMIZER CAN TAKE ADVANTAGE OF THESE UPDATED
CATALOG TABLES TO SELECT BEST ACCESS STRATEGY
EXAMPLE
CONTROL INFORMATION FOR RUNSTATS UTILITY
RUNSTATS TABLESPACE D2110K.TABSP
TABLE(ALL)
INDEX(ALL) ;
Runstats
The RUNSTATS utility reads tablespaces and indexes to collect statistics
describing the data. The main statistics collected include number of rows in the
table, number of pages that contain the rows of the table, number of distinct
values of indexed column , percentage of space occupied by rows etc.
RUNSTATS utility uses this information to update CATALOG tables.
In the previous example RUNSTATS utility is used for table space TABSP in
database D2110K. All tables in the tablespace are specified by TABLE(ALL)
keyword. Here you can specify the table name in parentheses after keyword
TABLE on which the utility has to run. You can obtain statistics on all indexes on
all tables in the named table space by specifying INDEX(ALL).The user can get
statistics of one more specific indexes by specifying them in parentheses after the
keyword INDEX .
The RUNSTATS utility is useful for finding out the free space remaining in a
tablespace and we use that information for reorganizing the tablespace.
REORG
REORG UTILITY IS USED TO REORGANIZES DATA ON
PHYSICAL STORAGE OF TABLES. DIFFERENT PHASES
OF REORG UTILITY ARE
 UNLOADS ROWS FROM A TABLE SPACE
 RELOADS ROWS IN A NEATER ARRANGEMENT
WITH FREE SPACE
 REBUILDS INDEXES
 DOES NOT VALIDATE DATA
CONTROL STATEMENTS FOR REORG UTILITY
REORG TABLESPACE D2110K.TABSP
LOG NO;
Reorg
The REORG online utility reorganizes a table space or index to improve access
performance and reclaim fragmented space. In addition, the utility can reorganize
a single partition of either a partitioned index or a partitioned table space.
REORG utility reorganizes table space or index as you specify in control
statements. When an index space only is reorganized then the data pages are
not processed. Only leaf pages which contains indexes are scanned.
Proper scheduling of reorganizations significantly improves performance of all
application programs.
In the given example REORG utility is run on tablespace TABSP in database
D2110K. If you want to reorganize an index then specify REORG INDEX (index
name) . LOG NO parameter is specified in the example to avoid writing data
records in the log while loading the tablespace.
12.
Advanced DB2
This section explains some of the advanced concepts in DB2. The detailed
discussions on indexes and DB2 locks are included. Advanced topics present in
this section are
12.1. More About Indexes
12.1.1.Example Of An Index
12.1.2.Clustered Indexes
12.1.3.Non Clustered Indexes
12.2. Special Registers
12.3. More About Locks
12.3.1.Modes Of Table And Tablespace Locks
12.3.2.Modes Of Row And Page Locking
12.3.3.Lock Mode Compatibility Of Table And Table Space Locks
12.3.4.Lockmode Compatibility Of Row And Page Locks
12.4. Invoking Online Utilities
More About Indexes
DB2 uses indexes not only to enforce uniqueness on column values, as for
primary keys, but also to cluster data, partition tables, and to provide access
paths to data for queries. Understanding some of the structure of DB2 indexes
can be important for achieving your best performance.
A table can have more than one index, and an index key can use one or more
columns. An index key is a column or an ordered collection of columns on which
an index is defined. A composite key is a key built on 2 to 64 columns.
The usefulness of an index depends on its key. Columns that you use frequently
in performing selection, join, grouping, and ordering operations are good
candidates for use as keys
DB2 allows you to enter duplicate values in a key column. If you do not want
duplicate values, use CREATE UNIQUE INDEX. If a table has a primary key, its
entries should be unique. Its uniqueness is enforced by defining a unique index
on the primary key columns,
EXAMPLE OF AN INDEX
25
8
.
.
8
17
. . 17
25
. . 25
61
86
33
40
. . 33
.
ROOT PAGE
61
40
70
.
. 61
75
86 INTERMEDIATE
PAGES
LEAF
PAGES
. . 70
. . 75 . . 86
POINTERS TO DATA RECORDS
DATA
PAGES
 THE INDEX IS STRUCTURED AS A B-TREE
 A RECORD IS LOCATED USING ROOT PAGE, INTERMEDIATE PAGES
AND LEAF PAGES
 THE PAGE SIZE OF AN INDEX IS 4KB
Example Of An Index
Indexes in DB2 are based on a structure known as B-Tree. Indexes can have
more than one level of pages. Index pages that point directly to the data in the
tables are called leaf pages. If the index has more than one leaf page, it must
have at least one non leaf page, containing entries that point to leaf pages. If it
has more than one non leaf page, the non leaf pages whose entries point directly
to leaf pages are said to be on the first level; there must be a second level of non
leaf pages to point to the first, and so on. The highest level contains a single
page, called the root page.
A typical index is shown in the figure, which is a multilevel, tree structured index
with the property that the tree is always balanced, that is that is all leaf entries in
the structure are equidistant from the root of the tree. and this property is
maintained as new entries are inserted into the tree and existing entries are
deleted
The root page is the top of the structure. The root page will contain an entry for
each non leaf or immediate page. The entry in the root page consists of the high
value contained on the intermediate page and a pointer to that page.
The immediate pages are similar in structure to the root page, expect that the
range of values addressed is more specific. The immediate page contains an
entry for each of the leaf pages addressed. The entry consists of the high value
contained on the leaf page and a pointer to this leaf page.
The leaf pages contain the RID, using which the record can be located in a table
space. The leaf pages collectively address the entire table.
CLUSTERED INDEXES
25
8
17
61
ROOT PAGE
33
40
INTERMEDIATE
PAGES
LEAF
PAGES
DATA
PAGES
 A CLUSTERING INDEX IS ONE IN WHICH THE RECORDS ARE
PHYSICALLY STORED IN DATA PAGES IN THE SEQUENTIAL ORDER OF
THEIR INDEX VALUES
 HIGH PERFORMANCE BECAUSE OF REDUCED I/O OPERATIONS
 EACH TABLE CAN HAVE ONLY ONE CLUSTERING INDEX
 CLUSTERING
INDEXES
ARE
EXTREMELY
IMPORTANT
FOR
OPTIMIZATION PURPOSES. OPTIMIZER WILL TRY TO CHOOSE AN
ACCESS PATH BASED ON THE CLUSTERING INDEX
Clustered Index
A clustering index is one for which the sequence defined by the index is the same
as or close to the physical sequence. The clustering holds the most potential for
performance gains. With a clustering index DB2 takes responsibility for
maintaining rows in sequence on the clustering index columns as long as there is
free space. DB2 maintains clustering by placing inserted rows in the indexed
column’s sequence on available free space in the data pages.DB2 can then
process the table in that order efficiently. If it is a non clustering index then DB2
has to reread data pages to identify all the qualifying rows, which will reduce
performance.
Clustering is valuable when DB2 must process a column’s values in sequence.
The SQL statements ORDER BY, GROUP BY, and DISTINCT require such
processing. If a column specified in these operation and there is not a suitable
index on the column, DB2 must sort it to put it in sequence before returning even
one row to the user. If there is a clustering index on that column DB2 uses this
column to retrieve the rows in sequence and return the rows immediately one by
one.
To specify a clustering index, use the CLUSTER clause in the CREATE INDEX
statement.
CREATE INDEX STATEMENT FOR A CLUSTERED INDEX
CREATE UNIQUE INDEX D2110N.I11010U1
ON D2110N.T11010
(TAB_INDEX)
BUFFERPOOL BP0
USING STOGROUP SGDB2O
PCTFREE 20
FREEPAGE 10
PRIQTY 40
SECQTY 20
CLOSE NO
CLUSTER;
NON CLUSTERED INDEXES
25
8
17
61
ROOT PAGE
33
40
INTERMEDIATE
PAGES
LEAF
PAGES
DATA
PAGES
 IN A NON CLUSTERED INDEX THE DATA ROWS DO NOT CORRESPOND
TO THE ORDER OF THE INDEX ENTRIES
SPECIAL REGISTERS
 A SPECIAL REGISTER IS A STORAGE AREA THAT DB2 DEFINES FOR A
PROCESS
 SPECIAL REGISTERS USED IN DB2 ARE










CURRENT DATE
CURRENT DEGREE
CURRENT PACKAGESET
CURRENT RULES
CURRENT SERVER
CURRENT SQLID
CURRENT TIME
CURRENT TIMESTAMP
CURRENT TIMEZONE
USER
Special Registers
DB2 supports a number of special registers. A special register is a storage area
that DB2 defines for a process. Wherever its name appears in an SQL statement,
the name is replaced by the register's value when the statement is executed.
Thus, the name acts like a function that has no arguments. (zero argument built in
scalar functions)
You can use the SET statement to change the current value of a register. Where
the register's name appears in other SQL statements, the current value of the
register replaces the name when the statement executes. A commit or rollback
operation has no effect on the values of special registers. Nor does any SQL
statement, other than SET statement can change a register value
CURRENT DATE, specifies the current date. The data type is DATE. The date is
derived by the DB2 that executes the SQL statement that refers to the special
register.
Example: Display the average age of employees.
SELECT AVG(YEAR(CURRENT DATE - BIRTHDATE))
FROM DSN8410.EMP;
CURRENT PACKAGESET specifies a string of blanks or the collection ID of the
package or packages that will be used to execute SQL statements. The data type
is CHAR(18).
EXAMPLE
Example: For executing a program, identify the collection ID for its package as
EWSA.
SET CURRENT PACKAGESET = 'EWSA';
CURRENT SQLID specifies the SQL authorization ID of the process. The data
type is CHAR(8). This SET statement is used to change the authorization id for a
process
Example: Set the SQL authorization ID to 'GROUP34' (one of the authorization
IDs of the process).
SET CURRENT SQLID = 'GROUP34';
CURRENT TIME, specifies the current time. The time is derived by the DB2 that
executes the SQL statement that refers to the special register. ,
Example: Display information about all project activities and include the current
date and time in each row of the result.
SELECT DSN8410.PROJACT.*, CURRENT DATE, CURRENT TIME
FROM DSN8410.PROJACT;
CURRENT TIMESTAMP, specifies the current timestamp. The data type is
TIMESTAMP. The timestamp is derived by the DB2 that executes the SQL
statement that refers to the special register.
Example: Display information about the full image copies that were taken
in the last week.
SELECT * FROM SYSIBM.SYSCOPY
WHERE TIMESTAMP > CURRENT TIMESTAMP - 7 DAYS;
CURRENT USER specifies the primary authorization ID of the process. The data
type is CHAR(8).
Example: Display information about tables, views, and aliases that are owned by
the primary authorization ID of the process.
SELECT * FROM SYSIBM.SYSTABLES WHERE CREATOR = USER;
MORE ABOUT LOCKS
MODES OF TABLE AND TABLESPACE LOCKS
IS
INTENT SHARE
IX
INTENT EXCLUSIVE
S
SHARE
U
UPDATE
SIX
SHARE WITH INTENT EXCLUSIVE
X
EXCLUSIVE
 IS :
S
THE LOCK OWNER CAN READ ANY DATA IN THE TABLE IF AN
LOCK CAN BE OBTAINED ON THE TARGET ROW OR PAGE
 IX :
THE LOCK OWNER CAN READ OR CHANGE ANY DATA IN THE
TABLE PROVIDED AN X LOCK CAN BE OBTAINED ON ROWS
OR PAGES TO BE CHANGED AND A U OR S LOCK CAN BE
OBTAINED ON ROWS TO BE READ
 SIX:
THE LOCK OWNER CAN READ ANY DATA IN THE TABLE AND
CHANGE ROWS IN THE TABLE PROVIDED IT CAN OBTAIN AN
X LOCK ON THE TARGET ROW OR PAGE FOR CHANGE. ROW
LOCKS ARE NOT OBTAINED FOR READING.
 S :
THE LOCK OWNER CAN READ ANY DATA IN THE TABLE AND
WILL NOT OBTAIN ROW OR TABLE LOCKS
 U :
THE LOCK OWNER CAN READ ANY DATA IN THE TABLE AND
MAY CHANGE DATA IF AN X LOCK ON THE TABLE CAN BE
OBTAINED. NO ROW OR PAGE LOCKS ARE OBTAINED
 X :
THE LOCK OWNER CAN READ OR UPDATE ANY DATA IN THE
TABLE. ROW LOCKS ARE NOT OBTAINED
Modes Of Table And Tablespace Locks
The locking modes IS IX SIX are used at the TABLE OR TABLESPACE level to
support row or page locks. They permit row or page level locking while preventing
more exclusive locks on the table by other applications.
When an application obtains an IS lock on a table, that application may acquire a
lock on a row or page for read only. Other applications can also read the same
row. In addition other applications can change data on other rows in the table.
An application having an IX lock on a table can change a row after acquiring a
row or page lock. Other applications can READ/CHANGE data on other rows in
the table.
When an application has an SIX lock on a table, that application may acquire a
lock on a row for change. Other application can only read other rows in the table.
The modes S U and X are used at the table level to enforce the strict table
locking strategy. No row or page level locking is used by application that possess
one of these locking modes.
When an application obtains an S lock on a table, that application can read any
data in that table. It will allow other applications to obtain locks that support read
only requests for any data in the entire table. No application can change any data
in the table until s lock is released.
When an application obtains a U lock on a table , that application can read any
data from that table and may eventually change data in that table by obtaining an
X lock. Other applications can only read data In that table.
When an application obtains an X lock on a table that application can read and
change any or all data in the table or tablespace . No other application can
access data in the entire table or tablespace for READ or CHANGE
MODES OF ROW AND PAGE LOCKING
ROW/PAGE LOCK
MINIMUM SUPPORTING
TABLE/TABLE SPACE LOCK
S
SHARE
IS
U
UPDATE
IX
X
EXCLUSIVE
IX
 S :
THE ROW IS BEING READ BY ONLY ONE APPLICATION AND IS
AVAILABLE FOR READ ONLY BY OTHER APPLICATIONS
 U :
THE ROW IS BEING READ BY ONE APPLICATION BUT IS
POSSIBLY TO BE CHANGED BY THAT APPLICATION. THE
ROW IS AVAILABLE FOR READ ONLY BY OTHER
APPLICATIONS
 X :
THE ROW IS BEING CHANGED BY ONE APPLICATION AND IS
NOT AVAILABLE FOR OTHER APPLICATION
 ROW LEVEL LOCKS ARE ONLY REQUESTED BY APPLICATIONS THAT
HAVE SUPPORTING LOCKS AT THE TABLE LEVEL
LOCK MODE COMPATIBILITY OF TABLE AND TABLE
SPACE LOCKS
MODE OF
LOCK A
MODE OF LOCK B
IS
S
IX
SIX
U
X
IS
YES
YES
YES
YES
YES
NO
S
YES
YES
NO
NO
YES
NO
IX
YES
NO
YES
NO
NO
NO
SIX
YES
NO
NO
NO
NO
NO
U
YES
YES
NO
NO
NO
NO
X
NO
NO
NO
NO
NO
NO
 THE SYMBOLS A AND B IN THE ABOVE DIAGRAM ARE USED TO
REPRESENT TWO DIFFERENT APPLICATIONS
 THIS CHART IS USEFUL TO DETERMINE IF TWO APPLICATION CAN
RUN CONCURRENTLY IF THEY ARE ACCESSING SAME TABLE WITH
THE GIVEN LOCK MODE AT THE SAME TIME.
Lock Mode Compatibility Of Table And Table Space Locks
If application A obtains an IS lock against a given table application B could obtain
an IS, S, IX, SIX or U lock against the same table at the same time. However an X
lock would not be permitted at the same time.
This particular example illustrates the concept of IS lock acting as supporting lock
for a lower level of locking. The only table lock that is not compatible is X lock
which would require exclusive lock use of the table. The presence of IS lock
indicates that a lower level of locking is required for this table and X lock is not
given.
Study of the chart reinforces the definitions of table and row lock modes
presented on previous pages. Review the row for IX under application A. Assume
that application A obtains an IX lock on table Y. This lock indicates that the
application intends to obtain locks to support change at the row level. The
application will allow other rows to be read and updated but will prevent access to
the target rows Examine each of the possible competing table locks that
application B might request
IS-- Intent to lock for read only at row level. This lock is compatible. There may be
contention at the row level if application A is changing the same row that
application B wants to read.
S-- Share lock at the table level. This lock is not compatible since the S lock
states that the entire table is available for read only by the application possessing
the lock and all other applications. The IX lock states that an intent to change data
at the row level which contradicts the requirement for read only. Therefore
application B could not obtain the S lock
IX-- Intent to lock for change at the row level. This lock is compatible. There may
be lock contention at the row level if application A is changing the same row that
application B wants to change.
SIX—The SIX lock states that lock request for changing data may be required at
the row level for the application processing the lock. In addition the rest of the
table is available for read only applications. The IX lock implies change at the row
level as well. Application B could obtain six lock on the table
U-- Read with intent to update. This table level lock states that the application
processing the lock may read any data and may potentially exchange the U lock
for an X lock. However until this exchange is done other applications can obtain
locks supporting read only. Application B would not be able to obtain the U lock at
the same time that application a possessed an IX lock on the same table.
X-- The application possessing this mode of lock on the table requires exclusive
use of the table. No other access is permitted. The ix lock possessed by an
application A would prevent application B from obtaining x lock
The same type of statements can be logically derived for the other rows in the
chart
LOCK MODE COMPATIBILITY OF ROW AND PAGE LOCKS
MODE
OF
LOCK A
MODE OF LOCK B
S
U
X
S
YES
YES
NO
U
YES
NO
NO
X
NO
NO
NO
 THIS CHART IS USEFUL TO DETERMINE IF TWO APPLICATION CAN
RUN CONCURRENTLY IF THEY ARE ACCESSING SAME ROW WITH THE
GIVEN LOCK MODE AT THE SAME TIME.
 CONSIDER AN APPLICATION A HAVING AN S LOCK ON ROW Y. THEN
ANOTHER APPLICATION B CAN ONLY GET LOCKS AND U ON THAT
ROW
 IF AN APPLICATION A HAS A SHARE LOCK ON A ROW IT, WILL ALLOW
OTHER APPLICATIONS TO READ THE SAME ROW. SO APPLICATION B
CAN GET AN S LOCK ON THE SAME ROW AT THE SAME TIME
 AN APPLICATION B CAN GET AN UPDATE LOCK ON A ROW WHICH IS
CURRENTLY LOCKED BY AN S LOCK OF APPLICATION A. IF THE
APPLICATION B WANTS TO CHANGE THAT ROW DB2 WILL WAIT UNTIL
THE S LOCK IS REMOVED AND IT WILL PROMOTE THE U LOCK TO AN
X LOCK.
 NO TWO APPLICATION CAN HAVE AN EXCLUSIVE LOCK ON THE SAME
ROW AT THE SAME TIME
 THE SAME TYPE OF STATEMENTS CAN BE LOGICALLY DERIVED FROM
OTHER ROWS OF ABOVE CHART.
Invoking Online Utilities
Creating utility control statements is the first step required to run an online utility.
Utility control statements define the function the utility job performs. Utility control
statements are read from the SYSIN input stream. The SYSIN stream can contain
multiple utility control statements. Control statements are different for each utility
and are explained in chapter 11
There are different methods of invoking DB2 online utilities. Commonly used
methods are using DB2I and IBM supplied JCL procedure DSNUPROC.
When you use DB2I (DB2 interactive ) panel for executing a utility you must
specify the name of the utility , the dataset which contains the control information
and other datasets needed by the the utility. Then you can execute the utility from
that panel.
DB2 on line utilities can be invoked using DSNUPROC procedure, For that you
must write and submit JCL, in your JCL, the EXEC statement invokes the
DSNUPROC procedure. You must give the control statements as input to
DSNUPROC and use the necessary datasets required for the execution of the
utility.
Sample JCL For Invoking Online Utilities
/EX6216X JOB SW301709,'I65000 XT01DL1',
// NOTIFY=&SYSUID,
// MSGCLASS=8,REGION=6M,
// TIME=15,LINES=200
//*
//PROCLIB JCLLIB ORDER=NTTU.SYS.PROCLIB
//*=============================================================
========
//*
°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°
//*
DB2 LOAD
//*
°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°
//*=============================================================
//*
//*------------------------------------------------------------------*/
//*
T00101
//* -------------------------------------------------------------------/*
//T00101R EXEC DSNUPROC,PARM='DB2O,I650001T001012'
//DSNUPROC.SYSIN DD *
RUNSTATS TABLESPACE D20015.S001501
TABLE (ALL) INDEX (ALL)
/*
//*