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Chapter 4
Database Management
Data Elements
Employee database
Payroll file
Employee
record1
Employee
record2
Remunerations
Employee
record3
Employee
record4
Name SSN Salary Name SSN Salary Name SSN Salary Name SSN Salary
Text: O’Brien : p. 144
Logical Data Elements

Field
represents an attribute of an entity

Record
Set of attributes that describe an entity

File
set of records of the same type
transaction file, archive file, ...

Database
integrated set of logically related files and the
rules they have to satisfy
Text: O’Brien : p. 145
Database
Employee database
Payroll data
Person data
Training data
Database Management
User Inquiry
Applications
Request
Database Management System
Corporate database
Text: O’Brien : p. 146
Example
CARS (model, #cylinders, origin, tax, fee)
Model #cyl
origin
tax fee
-----------------------------------------------------Rabit
4
Germany 15
30
Mustang 6
USA
0
45
Mirafiori 4
Italy
18
30
Accord
4 Japan
20
30
Cutlass
8 USA
0
60
Laguna
4 France
20
30
BMW
6 Germany
15
45
Velsatis 6 France
20
45
Velsatis 4 France
20
30
Origin  tax
#cyl
 fee
Example




Drivers having a driver-no , a name , a home address and a birthdate take out vehicles to make deliveries. A vehicle ( with a
unique id-number ) may be taken out of a depot whenever
available and kept out for any length of time . It is possible for a
vehicle to be taken out more than once on a given day by any
driver .
Each time a driver takes out a vehicle , he or she takes out a load
made up of any quantity of any number of item types , identified
by an item-number. Every time a vehicle is taken out , the driver
can incur expenses of allowed type (e.g. fuel cost ).
Each expense type has a code-no. The amount and code-no are
recorded each time an expense is incurred .
Any number of stops can be made during the trip . An address of
the stop is recorded for each stop , together with the quantity left
on that stop for each item type . A driver stops at an address only
one during a trip . However, stops can be made at the same
address on different trips.
Assignment
The university that has to keep track of student transcripts could use a
database structured as follows.
Student(Student Number - Last name - First name - SSSN - Street - Nr - Zip
Code - City - State - Country - Phone Number - Birth Date - Gender Class - Major - Minor)
Department(Depart. Code - Name - Office Nr - Office Code)
Course(Course Code - Course Name - Description - Credits - Department)
Section(Course Code - Section Nr - Instructor - Semester - Year)
Transcript(Student Number - Name - Course Code - Section Number Grade)
Work with DBMS-software
Operating
system
Databases
DBMS
Application
programs




Database development
Database inquiry
Database maintenance
Application development
Text: O’Brien : p. 147
Data
Dictionary
Dictionary Access
Text: O’Brien : p. 149
Database Inquiry

Query Languages
SQL
Select Name, department, salary
From Employee, Payroll
Where Employee.number = Payroll.number
and Function = “Analyst”.
QBE
Employee
Payroll
Name

number
num
number
num
function
“ Analyst”
department

salary

DBMS
User
interface
Query
language
Report
generator
DBMS
utilities
Application
generators
DBMS
kernel program
Data-dictionary
programs
Host-language
Program
Interface
Problems with files




Data redundancy
Non-integrated files
Data dependency
Other problems
 inconsistency
 integrity
Possible solutions :
database management system
• separation of files and applications
• specific database languages
• central dictionary
Characteristics of databases
Redundancy
. storage cost
. multiple update needed
. inconsistency possible
Data independence
The degree on which data structures can be modified
without affecting the related programs
Solution :
Database architecture with three levels
( conceptual, internal , external )
Types of Databases

Operational databases (subject area databases SADB)
 transaction databases, production databases
 employee database, stock database, ...

Analytical databases ( management databases )
 data retrieved from external and operational databases
 Accessible for OLAP, DSS, management information systems

Data Warehouses
 contain historical data from various operational and external
databases
 central source for standardized and integrated data for
management and users
 data mart is a limited version for a specific subject
 used for data mining
Text: O’Brien : p. 150
Types of Databases

(2)
Distributed databases
 mostly for local needs, can be copies
 consistency problems
 distributed over servers
 related, eventually via WWW or intranet

Personal databases for end users
 various data gathered by users on their workstations
 eventual with spreadsheet or DBMS

External databases
 often access charge
 statistical , bibliographical
Text: O’Brien : p. 151-153
Types of Databases
Client-PC
or NC
End-user
databases
Text: O’Brien : p. 151
External
databases
Network
server
Distributed
databases
(3)
Datawarehouse
Operational
databases
Management
databases
Hypermedia DB on the WEB
WEBbrowser
Internet
intranet
extranet
Web-server
software
Client-PC
or NC
Network
server
parts of a
Web-information system
Text: O’Brien : p. 153
Hypermedia
database
Data Resource Management
Data
administration
•Policy governing data ownership
and access control
•Data Resource Requirement Planning
•Data model and data architecture
Data Planning
Database Administration
Text: O’Brien : p. 154
•Strategic and technical
database planning
•Define applications
•Procedures for data retention
•Operational procedures
•Physical database
•Logical database
•Data dictionary
•HW and SW
Benefits and Limitations

Benefits of a DBMS
 reduces data redundancy and integrates data
 data accessible from all programs
 programs not dependent on data format
 query/answer and reporting facilities
 easier application development and programming
 better integrity and security

Limitations of a DBMS
 increased complexity of the technology
 development of large databases is difficult and expensive
 slower than file management systems due to additional layer
 more sensible for fraud, errors and failures
Technical Principles
of database management
Files
Physical
Logical
A
D
B
C
C
B
E
A
D
E
Aspects of file usage
File activity
input
2000
orders
processing
20%
revenue state
1 instruction
inquiry
1 inquiry
Accessibility
Evolution
Client
file
100%
10000
records
0.01%
What is a database ?
1. A database is a set of data which are modifiable and
accessible by a computer program.
text, image, voice, structured information.
2. A database is a set of data which are
. structured
. integrated
. non-redundant
. shared
It is a source of data for a large number of different
applications and for a variety of users.
Database
type
Employee
Number
Name City
STUDIES
Diploma
CHILDREN
year
occurrence
12 Duval Rome
16 Krols Dublin
38 Smets Berlin
First name
Birthday
college
87
master math 94
econ
90
Accounting 94
college
91
Bache elec
94
john 120694
inge 241198
lidy 070296
Carl 040894
Supplier file
SNUMBER
SNAME
S1
S2
S3
S4
S5
De Smet
Janssens
Blanchart
Clark
Adams
STATUS
20
10
30
20
30
CITY
London
Paris
Paris
London
Athens
Supplier file with index on city
City-index
Supplier file
Athens .
SNUM LNAME
London .
S1
De Smet
20
London
London .
S2
Janssens
10
Paris
Paris
.
S3
Blanchart
30
Paris
Paris
.
S4
Clark
20
London
S5
Adams
30
Athens
STATUS
City
Index on city and index on status
Supplier file
City-index
LNUM LNAME
Athens .
London .
London .
Paris
Paris
.
.
STATUS
CITY
S1
De Smet
20
London
S2
Janssens
10
Paris
S3
Blanchart
30
Paris
S4
Clark
20
London
S5
Adams
30
Athens
Status-index
.
10
.
20
.
20
.
30
.
30
Non-dense index
Supplier file

SNUM SNAME
S1
De Smet
S4 .

S2
Janssens
10
Paris
S5 .

S3
Blanchart
30
Paris

S2 .
STATUS
20
CITY
London

S4
Clark
20
London

S5
Adams
30
Athens

block 1
block 2
block 3
File Organization: Indexed-sequential
Bens
Dooms
Fagin
parameters
- index block size
- data block size
multi-level
index blocks
Adams
Albert
Bens
data
blocks
Ace
Adams
Ademar Behr
Bens
Aerts
Albert
Bodoo
Claes
Codd
Dooms
Bodoo
Ernest
Fagin
Fully Inverted file
SNAME-index
De Smet
Janssens
Blanchart
Clark
Adams
S1->
S2->
S3->
S4->
S5->
STATUS-index
10 S1->
20 S1->,S4->
30 S3->,S5->
City-index
Supplierfile
Athens S5->
S1
London S1->,S4->
S2
Paris
S2->,S3->
S3
S4
S5
Sample file
Supplier file
SNUMBER
SNAME
S1
S2
S3
S4
S5
De Smet
Janssens
Blanchart
Clark
Adams
STATUS
20
10
30
20
30
CITY
London
Paris
Paris
London
Athens
Organization with key transformation
0
1
S300 Blanchart 30 Paris
2
3
4
5
S200 Janssens 10 Paris
6
7
S500
Adams
30
Athens
8
9
S100 De Smet
10
S400
12
11
Clark
20 London
20 London
Hierarchical Database Structure
Department
data element
Project A
data element
Employee 1
Text: O’Brien : p. 158
Project B
data element
Employee 2
Network Database Structure
Department A
Employee 1
Employee 2
Project
A
Text: O’Brien : p. 158
Department B
Employee 3
Project
B
Relational Structure
Department D#
D1
D2
D3
D4
D5
Employee
Text: O’Brien : p. 158
DName location
Manager
E# EName FUNCTION SALARY
E1
E2
E3
E4
E5
D#
D1
D1
D2
D3
D3
Object Oriented Structure
Attributes
Object class
•client
Bank account •status
•interest
Operations
•payment
•withdrawal
Object class
Checking account
Attributes
•credit limit
•monthly statement
Operations
•calculate interest
•print status
Text: O’Brien : p. 161
Inheritance
Object class
Saving account
Attributes
•number of withdrawals
•Quarterly statement
Operations
•calculate interest
•print quarterly statement
Database Development
1.Data Planning
2. Specification gathering
3. Conceptual design
4. Physical design
5. Logical design
Text: O’Brien : p. 164
Data Modeling
Entity-relation diagram
EMPLOYEE
SUPERVISED
by
Allocated
MANAGER
STAFFER
FREELANCER
Text: O’Brien : p. 165
COMPANY
CAR
Authorizes
submits
INVOICE