Download Distributed Database Applications

Distributed Database
Applications
COSC 5050
Week Seven
Outline
Dynamic SQL and dynamic PL/SQL
NDS statements
EXCUTE IMMEDIATE
OPEN FOR
Oracle's object features
Globalization and localization
Webster University
Distributed Database Applications
Jiangping Wang
Dynamic SQL and PL/SQL
Constructed and executed at runtime
Stored in character strings that are input
to, or built by, the program at runtime
Execute DDL statements
Build back-ends applications
DBMS_SQL package
Native Dynamic SQL (NDS)
Webster University
Distributed Database Applications
Jiangping Wang
NDS Statement
Native dynamic SQL
Is an integral part of the PL/SQL language itself
Significantly simpler to user and faster
Non-query statements (DML and DDL) and PL/SQL
blocks
EXECUTE IMMEDIATE statement
Execute a specified SQL statement immediately
OPEN FOR statement
Perform multiple-row dynamic queries
Webster University
Distributed Database Applications
Jiangping Wang
DDL, DML, Anonymous Blocks
declare
l_sqlstring varchar2(200);
l_plsqlblock varchar2(200);
begin
execute immediate
'create table execute_table (col1 varchar(10))';
for l_counter in 1..10 loop
l_sqlstring := 'insert into execute_table
values (''row ' || l_counter || ''')';
execute immediate l_sqlstring;
end loop;
l_plsqlblock :=
'begin
for l_rec in (select * from execute_table) loop
dbms_output.put_line(l_rec.col1);
end loop;
end;';
execute immediate l_plsqlblock;
execute immediate 'drop table execute_table';
end;
Webster University
Distributed Database Applications
Jiangping Wang
EXECUTE IMMEDIATE Statement
execute immediate
'create index emp_u_1 on employee (last_name)';
create or replace procedure execddl
(ddl_string in varchar2)
is
begin
execute immediate ddl_string;
end;
exec execddl(
'create index emp_u_i on employee(last_name)');
Webster University
Distributed Database Applications
Jiangping Wang
EXECUTE IMMEDIATE Statement
CREATE OR REPLACE FUNCTION tabCount (
tab IN VARCHAR2,
whr IN VARCHAR2 := NULL,
sch IN VARCHAR2 := NULL)
RETURN INTEGER
IS
retval INTEGER;
BEGIN
EXECUTE IMMEDIATE
'SELECT COUNT(*)
FROM ' || NVL (sch, USER) || '.' || tab ||
' WHERE ' || NVL (whr, '1=1')
INTO retval;
RETURN retval;
END;
/
if tabcount ('emp', 'deptno = ' || v_dept) > 100 then
dbms_output.put_line('growing fast!');
end if;
Webster University
Distributed Database Applications
Jiangping Wang
EXECUTE IMMEDIATE Statement
Bind Variable
CREATE OR REPLACE FUNCTION updNVal (
tab IN VARCHAR2,
col IN VARCHAR2,
val IN NUMBER,
PL/SQL engine replaces the various
whr IN VARCHAR2 := NULL,
placeholders with the values in the
sch IN VARCHAR2 := NULL)
USING clause
RETURN PLS_INTEGER
IS
BEGIN
EXECUTE IMMEDIATE
'UPDATE ' || NVL (sch, USER) || '.' || tab ||
'
SET ' || col || ' = :the_value
WHERE ' || NVL (whr, '1=1')
USING val;
RETURN SQL%ROWCOUNT;
END;
/
Webster University
Distributed Database Applications
Jiangping Wang
EXECUTE IMMEDIATE Statement
Bind Variable
CREATE OR REPLACE PROCEDURE run_9am_procedure (
id_in
IN
employee.employee_id%TYPE,
hour_in
IN
INTEGER)
IS
v_apptcount
INTEGER;
v_name
VARCHAR2 (100);
BEGIN
EXECUTE IMMEDIATE
'BEGIN ' || TO_CHAR (SYSDATE, 'DAY') ||
'_set_schedule (:id, :hour, :name, :appts); END;'
USING IN id_in, IN hour_in, OUT v_name, OUT v_apptcount;
DBMS_OUTPUT.put_line (
'Employee ' || v_name || ' has ' || v_apptcount ||
' appointments on ' || TO_CHAR (SYSDATE));
END;
/
Webster University
Distributed Database Applications
Jiangping Wang
OPEN FOR Statement
Extend cursor variables to support
dynamic SQL
create or replace procedure show_parts_inventory (
parts_table in varchar2,
where_n in varchar2 := null)
is
type query_curtype is ref cursor;
dyncur query_curtype;
begin
open dyncur for
‘select * from ’ || parts_table
‘where ’ || nvl(where_in, ‘1=1’);
…
end;
Webster University
Distributed Database Applications
Jiangping Wang
OPEN FOR Statement
create or replace procedure show_employee (
table_in in varchar2,
where_in in varchar2 := null)
is
type query_curtype is ref cursor;
dyncur query_curtype;
emp employee%rowtype;
begin
open dyncur for
'select * from ' || table_in ||
' where ' || nvl (where_in, '1=1');
dbms_output.put_line('Employee list:');
loop
fetch dyncur into emp;
exit when dyncur%notfound;
dbms_output.put_line(emp.lname || ' ' || emp.fname);
end loop;
close dyncur;
end;
/
Webster University
Distributed Database Applications
Jiangping Wang
Multirow Queries with Cursor
Variables
CREATE OR REPLACE PROCEDURE showcol (
tab IN VARCHAR2,
col IN VARCHAR2,
whr IN VARCHAR2 := NULL)
IS
TYPE cv_type IS REF CURSOR;
cv cv_type;
val VARCHAR2(32767);
BEGIN
OPEN cv FOR
'SELECT ' || col || ' FROM ' || tab || ' WHERE ' || NVL (whr, '1 = 1');
LOOP
FETCH cv INTO val;
EXIT WHEN cv%NOTFOUND;
IF cv%ROWCOUNT = 1
THEN
DBMS_OUTPUT.PUT_LINE (RPAD ('-', 60, '-'));
DBMS_OUTPUT.PUT_LINE ('Contents of '||UPPER(tab)||'.'||UPPER(col));
DBMS_OUTPUT.PUT_LINE (RPAD ('-', 60, '-'));
END IF;
DBMS_OUTPUT.PUT_LINE (val);
END LOOP;
CLOSE cv;
END;
/
Jiangping Wang
Webster University
Distributed Database Applications
FETCH into Variables
Declare
type cv_type is ref cursor;
cv cv_type;
mega_bucks company.ceo_compensation%type;
achieved_by company.cost_cutting%type;
Begin
Open cv for
‘select ceo_compensation, cost_curtting from
company where ’ || nvl (whr, ‘1=1’);
loop
fetch cv into mega_bucks, achieved_by;
Webster University
Distributed Database Applications
Jiangping Wang
FETCH into Records
Declare
type cv_type is ref cursor;
cv cv_type;
ceo_info company%rowtype;
Begin
Open cv for
‘select * from from company where ’ || nvl
(whr, ‘1=1’);
loop
fetch cv into ceo_info;
Webster University
Distributed Database Applications
Jiangping Wang
FETCH into Records
create or replace package company_struc
is
type dynsql_curtype is ref cursor;
type ceo_info_rt is record (
mega_bucks company.ceo_compensation%type,
achieved_by company.cost_cutting%type);
declare
cv company_struc.dynsql_curtype;
rec company_struc.ceo_info_rt;
begin
open cv for
‘select ceo_eompensatin, cost_cutting from company
where ’ || nvl (whr, ‘1=1’);
loop
fetch cv into rec;
Webster University
Distributed Database Applications
Jiangping Wang
The USING Clause in OPEN FOR
OPEN cv FOR
'SELECT ' || col ||
' FROM ' || tab ||
' WHERE ' || dtcol ||
' BETWEEN TRUNC (:startdt)
AND TRUNC (:enddt)'
USING dt1, NVL (dt2, dt1+1);
LOOP
FETCH cv INTO val;
EXIT WHEN cv%NOTFOUND;
IF cv%ROWCOUNT = 1
THEN
…
Webster University
Distributed Database Applications
Jiangping Wang
Binding Variables
Binding utilizes placeholders and USING clause
EXECUTE IMMEDIATE
'UPDATE ' || tab || ' SET sal = :new_sal' USING v_sal;
Concatenation adds values directly to the SQL
string
EXECUTE IMMEDIATE
'UPDATE ' || tab || ' SET sal = ' || v_sal;
Binding is faster
Binding is easier to write and maintain
Binding negates the chance of code injection
Webster University
Distributed Database Applications
Jiangping Wang
Code Injection
CREATE OR REPLACE PROCEDURE get_rows (
ssn_in in VARCHAR2
)
IS
l_where VARCHAR2(32767);
BEGIN
l_where := 'ssn = ' || ssn_in;
EXECUTE IMMEDIATE
'DECLARE l_row employee%ROWTYPE;
BEGIN
SELECT * INTO l_row
FROM employee WHERE ' || l_where || ';
dbms_output.put_line(l_row.lname);
END;';
END get_rows;
/
Webster University
Distributed Database Applications
Jiangping Wang
Avoid Code Injection
CREATE OR REPLACE PROCEDURE get_rows (
ssn_in in VARCHAR2
)
IS
l_where VARCHAR2(32767);
BEGIN
l_where := 'ssn = :ssnumber';
EXECUTE IMMEDIATE
'DECLARE l_row employee%ROWTYPE;
BEGIN
SELECT * INTO l_row
FROM employee WHERE ' || l_where || ';
dbms_output.put_line(l_row.lname);
END;' USING ssn_in;
END get_rows;
/
Webster University
Distributed Database Applications
Jiangping Wang
Argument Modes
IN, OUT, IN OUT
create or replace procedure wrong_incentive(
company_in in integer,
new_layoffs in number)
is
sql_string varchar2(2000);
sal_after_layoffs number;
begin
sql_string :=
‘update ceo_compensation
set salary = salary + 10 * :layoffs
where company_id = :company
returning salary into :newsal’;
execute immediate
sql_string
using new_layoffs, company_in, out sal_after_layoffs;
dbms_output.put_line
(ceo compensation after latest round of layoffs $’ ||
sal_after_layoffs);
end;
Webster University
Distributed Database Applications
Jiangping Wang
Duplicate Placeholders
create or replace procedure updnumval (
Dynamic SQL, supply
col_in in varchar2,
for each placeholder
start_in in date,
end_in in date,
val_in in number)
is
dml_str varchar2(32767) := 'update emp set ' || col_in || ' := :val
where hiredate between :lodate and :hidate and :val is not null';
begin
execute immediate dml_str using val_in, start_in, end_in, val_in;
end;
an argument
create or replace procedure updnumval (
col_in in varchar2,
Dynamic PL/SQL block, supply an
start_in in date,
argument for each unique placeholder
end_in in date,
val_in in number)
is
dml_str varchar2(32767) :=
'begin
update emp set ' || col_in || ' := :val
where hiredate between :lodate and :hidate and :val is not null;
end; ';
begin
execute immediate dml_str using val_in, start_in, end_in;
end;
Webster University
Distributed Database Applications
Jiangping Wang
Dynamic SQL and Static SQL
More versatile than plain embedded
SQL programs
Can be built interactively with input
from users having little or no
knowledge of SQL
For highly flexible applications
Require complex coding
Use of special data structures
More runtime processing
Webster University
Distributed Database Applications
Jiangping Wang
Oracle's Object Features
Object programming features
Creating base type and subtype
Creating object
Storing, retrieving, and using persistent
objects
Webster University
Distributed Database Applications
Jiangping Wang
Object Programming Features
Webster University
Distributed Database Applications
Jiangping Wang
Object Programming Features
Webster University
Distributed Database Applications
Jiangping Wang
Library Catalog Type Hierarchy
Webster University
Distributed Database Applications
Jiangping Wang
Creating Base Type
CREATE OR REPLACE TYPE catalog_item_t AS OBJECT (
id INTEGER,
title VARCHAR2(4000),
NOT INSTANTIABLE MEMBER FUNCTION ck_digit_okay
RETURN BOOLEAN,
MEMBER FUNCTION print
RETURN VARCHAR2
) NOT INSTANTIABLE NOT FINAL;
/
Webster University
Distributed Database Applications
Jiangping Wang
Creating Subtype
CREATE OR REPLACE TYPE book_t UNDER catalog_item_t (
isbn VARCHAR2(13),
pages INTEGER,
CONSTRUCTOR FUNCTION book_t (
id IN INTEGER DEFAULT NULL,
title IN VARCHAR2 DEFAULT NULL,
isbn IN VARCHAR2 DEFAULT NULL,
pages IN INTEGER DEFAULT NULL)
RETURN SELF AS RESULT,
OVERRIDING MEMBER FUNCTION ck_digit_okay
RETURN BOOLEAN,
OVERRIDING MEMBER FUNCTION print
RETURN VARCHAR2
);
/
Webster University
Distributed Database Applications
Jiangping Wang
Creating Subtype
CREATE OR REPLACE TYPE serial_t UNDER catalog_item_t (
issn VARCHAR2(10),
open_or_closed VARCHAR2(1),
CONSTRUCTOR FUNCTION serial_t (
id IN INTEGER DEFAULT NULL,
title IN VARCHAR2 DEFAULT NULL,
issn IN VARCHAR2 DEFAULT NULL,
open_or_closed IN VARCHAR2 DEFAULT NULL)
RETURN SELF AS RESULT,
OVERRIDING MEMBER FUNCTION ck_digit_okay
RETURN BOOLEAN,
OVERRIDING MEMBER FUNCTION print
RETURN VARCHAR2
) NOT FINAL;
/
Webster University
Distributed Database Applications
Jiangping Wang
Creating Object
DECLARE
generic_item catalog_item_t;
abook book_t;
BEGIN
abook := NEW book_t(title => 'Out of the Silent Planet',
isbn => '0-6848-238-02');
generic_item := abook;
DBMS_OUTPUT.PUT_LINE('BOOK: ' || abook.print());
DBMS_OUTPUT.PUT_LINE('ITEM: ' || generic_item.print());
END;
Webster University
Distributed Database Applications
Jiangping Wang
Storing Persistent Objects
CREATE TABLE catalog_items OF catalog_item_t
(CONSTRAINT catalog_items_pk PRIMARY KEY (id));
CREATE TABLE my_writing_projects (
project_id INTEGER NOT NULL PRIMARY KEY,
start_date DATE,
working_title VARCHAR2(4000),
catalog_item catalog_item_t);
DESC catalog_items
desc my_writing_projects
INSERT INTO catalog_items
VALUES (NEW book_t(10003, 'Perelandra', '0-684-82382-9', 222));
INSERT INTO catalog_items
VALUES (NEW serial_t(10004, 'Time', '0040-781X', 'O'));
Webster University
Distributed Database Applications
Jiangping Wang
Retrieving Persistent Objects
The VALUE function
Accepts a single argument, which must be
a table alias in the current FROM clause
Returns an object of the type on which the
table is defined
SELECT VALUE(c)
FROM catalog_items c;
SELECT VALUE(c).id, VALUE(c).print()
FROM catalog_items c;
Webster University
Distributed Database Applications
Jiangping Wang
Retrieving Persistent Objects
DECLARE
catalog_item catalog_item_t;
CURSOR ccur IS
SELECT VALUE(c) FROM catalog_items c;
BEGIN
OPEN ccur;
FETCH ccur INTO catalog_item;
DBMS_OUTPUT.PUT_LINE('I fetched item #' || catalog_item.id);
CLOSE ccur;
END;
Webster University
Distributed Database Applications
Jiangping Wang
Object Downcasting
The TREAT function
Treat a generic base type object as the
more narrowly defined subtype object
DECLARE
book book_t;
catalog_item catalog_item_t := NEW book_t();
BEGIN
book := TREAT(catalog_item AS book_t);
END;
/
Webster University
Distributed Database Applications
Jiangping Wang
Test Object Type
DECLARE
CURSOR ccur IS
SELECT VALUE(c) item FROM catalog_items c;
arec ccur%ROWTYPE;
BEGIN
FOR arec IN ccur
LOOP
CASE
WHEN arec.item IS OF (book_t)
THEN
DBMS_OUTPUT.PUT_LINE('Found a book with ISBN '
|| TREAT(arec.item AS book_t).isbn);
WHEN arec.item IS OF (serial_t)
THEN
DBMS_OUTPUT.PUT_LINE('Found a serial with ISSN '
|| TREAT(arec.item AS serial_t).issn);
ELSE
DBMS_OUTPUT.PUT_LINE('Found unknown catalog item');
END CASE;
END LOOP;
END;
Webster University
Distributed Database Applications
Jiangping Wang
Globalization and Localization
Unicode support
Variable precision
Single-byte vs. multi-byte
Sorting order
Non-character data
Date and time
Currency
Webster University
Distributed Database Applications
Jiangping Wang
Character Codes
ASCII
The ASCII Character set: characters 32 – 127.
Webster University
Distributed Database Applications
Jiangping Wang
ASCII 1967
0
1
2
3
4
5
6
7
8
9
0 NUL SOH STX ETX EOT ENQ ACK BEL BS HT
1 DLE DC1 DC2 DC3 DC4 NAK SYN ETB CAL EM
2 sp ! ” # $ % & ’
(
)
3 0 1 2 3 4 5 6 7 8 9
4 @ A B C D E F G H I
A
B
C
D
E
F
LF
VT
FF
CR
SO
SI
SUB ESC
FS
GS
RS
US
/
?
O
*
:
J
+
;
K
,
<
L
=
M
.
>
N
5
P
Q
R
S
T
U
V
W
X
Y
Z
[
\
]
^ _
6
7
`
p
a
q
b
r
c
s
d
t
e
y
f
v
g
w
h
x
i
y
j
z
k
{
l
|
m
}
n
~
Webster University
Distributed Database Applications
o
DEL
Jiangping Wang
ISO 8859-1
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
0
1
2 sp
3 0
4 @
!
1
A
”
2
B
#
3
C
$
4
D
%
5
E
&
6
F
’
7
G
(
8
H
)
9
I
*
:
J
+
;
K
,
<
L
=
M
.
>
N
/
?
O
5
Q
R
S
T
U
V
W
X
Y
Z
[
\
]
^ _
6 ` a b
7 p q r
8
9
A NBSP ¡ ¢
B ° ± ²
C À Á Â
D Ð Ñ Ò
E à á â
F ð ñ ò
Webster University
c
s
d
t
e
y
f
v
g
w
h
x
i
y
j
z
k
{
l
|
m
}
n
~
£
³
Ã
Ó
ã
ó
¤ ¥
¦
§ ¨ © ª
´ µ ¶ ·
¸
¹
º
Ä Å Æ Ç È É Ê
Ô Õ Ö × Ø Ù Ú
ä å æ ç è é ê
ô Distributed
õ ö Database
÷ Applications
ø ù ú
«
»
Ë
Û
ë
û
¬
¼
Ì
Ü
ì
ü
½
Í
Ý
í
ý
® ¯
¾ ¿
Î
Ï
Þ ß
î
ï
þ Jiangping
ÿ
Wang
P
o
DEL
Unicode Support
Unicode is a standard for representing
characters
Character encoding with UTF
UTF-8
UTF-16
UTF-32
Webster University
Distributed Database Applications
Jiangping Wang
Unicode Encoding Space
F, 10: Private Use Planes
E: Supplementary Special-Purpose Pla
Unassigned
2: Supplementary Ideographic Plane
1: Supplementary Multilingual Plane
0: Basic Multilingual Plane
Webster University
Distributed Database Applications
Jiangping Wang
Encoding Characters
Associating characters with values in
the code space
Webster University
Distributed Database Applications
Jiangping Wang
Encoding Forms
Three equivalent and interconvertible
binary representations
Webster University
Distributed Database Applications
Jiangping Wang
Oracle Character Sets
Character set
NLS_CHARACTERSET
NLS_NCHAR_CHARACTERSET
Data types
CHAR and VARCHAR
NCHAR and NVARCHAR
Webster University
Fixed-length
Variable-length
Database character set
CHAR
VARCHAR2
National character set
NCHAR
NVARCHAR2
Distributed Database Applications
Jiangping Wang
Oracle Character Sets
Webster University
Distributed Database Applications
Jiangping Wang
Unicode Support
Webster University
Distributed Database Applications
Jiangping Wang