PLnew

8/4/2019 PLnew

http://slidepdf.com/reader/full/plnew 1/191

PL/SQL

Ankita Kachwaha

8/4/2019 PLnew


Disadvantages of SQL

No pr ocedural capabilities.

SQL statements are passed to oracle engineone at a time.

No facility to handle err ors.

8/4/2019 PLnew


Advantages of PL/SQL

Pr ovide facility of condition checking, looping,

and branching.

Entire block of statement is passed to oracleengine.

Permit dealing with err ors.

All so

rto

f calculatio

n can be do

ne quickly andefficiently.

PL/SQL blocks are portable.

8/4/2019 PLnew


PL/SQL block

BEGIN

END;

EXCEPTION

DECLARE

END;

««

BEGIN

EXCEPTION

«

8/4/2019 PLnew


DECLARE (Optional)

Variables, cursors, user-defined exceptions

BEGIN (Mandatory)SQL statements

PL/SQL statements

EXCEPTION (Optional)

Actions to perf orm when err ors occur

END; (Mandatory)

8/4/2019 PLnew


Execution environment

PL/SQL

block

PL/SQL engine

Oracle server

Procedural

statement

executor

PL/SQL

SQL

SQL statement executor

PL/SQL

block

8/4/2019 PLnew


Character set

Uppercase / lower case alphabet.

Numbers

Symbols

8/4/2019 PLnew


Variable declaration

Var_name [constant] data type [not null]

[:=value];

8/4/2019 PLnew


Data type in pl /sql

Scalar type

Composite type

LOB type Reference type

Object type

8/4/2019 PLnew


Scalar type

Number (p, s)

Declaration value stored value

Number 1234.678 1234.678

number (3) 123 123

number (3) 1234 err or

number (4,3) 123.456 err or- exceed precision

number (4,3) 1.234567 1.235

number (7, 2) 12345.67 12345.67

number (4, -3) 1234 1000

8/4/2019 PLnew


Char

Varchar2

Date Long

Long raw/raw

Boolean (true, false, null)

8/4/2019 PLnew


Composite type

Packages

8/4/2019 PLnew


LOB type

BFILE

LOB

CLOB

NLOB

8/4/2019 PLnew


REFERENCE TYPE

CURSOR

8/4/2019 PLnew


OBJECT TYPE

% type

This declares a variable of the same type aspreviously defined variable or column of a

table or view.

Identifier Table.column_name%TYPE;

v_min_balance v.balance%TYPE := 10;

8/4/2019 PLnew


Variable

Must begin with character and have

maximum length of 29.

Reser ve words can be used as variable butmust be enclosed in double quote.

Spaces and special symbol not allowed

except underscore.

Var_name data type(size) [default value];

Var_name data type(size)[ :=value];

8/4/2019 PLnew


Constraint

Constraint must be assigned values

immediately.

Pi const number (4,2):=3.14;

8/4/2019 PLnew


Displaying messages

DBMS_ OUTPUT is a package.

PUT_LINE is a pr ocedure which accept onlysingle parameter of character type.

Set ser ver

output

on;

8/4/2019 PLnew


Reading value of variable

Variable name:=& variable name;

8/4/2019 PLnew


Comment

--

/*««««««««*/

8/4/2019 PLnew


SQL> SET SERVEROUTPUT ONSQL>

SQL> BEGIN2 DBMS_OUTPUT.PUT_LINE(4 * 2);

3 DBMS_OUTPUT.PUT_LINE(24 / 3);4 DBMS_OUTPUT.PUT_LINE(4 + 4);5 DBMS_OUTPUT.PUT_LINE(16 - 8);

6 END;7 /

88

88

8/4/2019 PLnew


SQL> set ser ver output onSQL> declare

2 v _length NUMBER :=5.5;3 v _width NUMBER :=3.5;4 v _area NUMBER;5 begin

6 v _area:=v _length*v _width;7 DBMS_ OUTPUT.put_line(' Area:'||v _ar ea);8 end;

9 / Area:19.25

8/4/2019 PLnew


Assign SQL query results to

PL/SQL variables

SQL> declare2 v_name VARCHAR2(256);3 begin4 select first_name

5 into v_name6 from employee7 where id=7;8 DBMS_OUTPUT.put_line('v_name:'||v_name);9

10 end;11 /v_name:David

8/4/2019 PLnew


Scope Rules

Scope means the range of code within

which a given identifier can be referenced.

An identifier can be referenced only by codeexecuting inside the block in which the

identifier was declared.

An identifier could be a variable name, or a

pr ocedure name, function name.

8/4/2019 PLnew


Demonstrate nested PL/SQL

blocks

SQL> declare2 v _custno NUMBER := 100;3 begin4 dbms_ output.put_line(v _custno) ;5 declare6 v _state CHAR(2):= 'NY' ;7 begin8 dbms_ output.put_line(v _custno || v _state) ;9 end ;

10 end ;11 /100100NY

8/4/2019 PLnew


dbms_utility.get_time

start number default dbms_utility.get_time;

8/4/2019 PLnew


Conditional control

If <condition> then

<action>

elsif <condition> then<action>

else

<action>end if;

8/4/2019 PLnew


Example

Declare

cur_bal number(10,2);

acno number(4);

Begin

select bal into cur_bal from acct whereacctno=141;

if cur_bal < 5000 then

update acct set bal=bal-100 where accno=141;end if;

End;

8/4/2019 PLnew


Type of loops

Simple loop

While loop

For loop

8/4/2019 PLnew


Simple loop

Loop

<body of loop>

<end loop>

8/4/2019 PLnew


Example

Declare

i number:=0;

Begin

loop

i:= i+2;

exit when i>10;

end loop;dbms_ output.put_line(µloop end when i=µ||to _char (i));

End;

8/4/2019 PLnew


While loop

While <condition>

loop

<action>end loop;

8/4/2019 PLnew


example

Declare

pi constant number(4,2):=3.14;

radius number(5);

area number(14,2);begin

while radius <=7

Loop

A

rea:=pi*power(radius,2);Insert into areas values (radius, area);

radius:=radius+1;

end loop;

End;

8/4/2019 PLnew


For loop

For variable in [reverse] start ..end

loop

<action>end loop;

8/4/2019 PLnew


Example

Declare

no varchar2(5):=µ65432¶;

str_len number(4);

reverse varchar2(5);Begin

str_len:=length(no);

for count in reverse 1..str_len

loopreverse:=reverse||substr(no,count,1);

end loop;

dbms_output.put_line(µreverse no is µ||reverse);

End;

8/4/2019 PLnew


Goto statement

Goto <block name>

8/4/2019 PLnew


Example

Declare

no number (5);

Beginno:=&no;

if no>5 then

goto mark;

end if;

dbms_ output.put_line(µmore than 5¶);

<<mark>>

End;

8/4/2019 PLnew


Restriction on go to

Begin

goto inner block; -- illegal cannot branch to an inner block

begin

«..

<<inner block >>

«..

end;

goto innerif ; -- illegal cannot branch into an if statement

if 9>3 then

««.

<<innerif >>

««..

end if;

end;

8/4/2019 PLnew


Begin

if 9>3 then

goto next; -- illegal to branch from one if clause to another

else

<<next>>;

«««

end if;

end;

8/4/2019 PLnew


Illegal to branch from an exception

handler to current block

Declare

««...

begin

««..<<back>>

««..

exception

«««

goto back;

end;

8/4/2019 PLnew


Labeling

Labeled statement

Labeled block

Labeled loops

8/4/2019 PLnew


Labeled statement

«««..

«««..

<<table_select>>select * fr om emp;

«««..

«««..

8/4/2019 PLnew


Labeled block

<<block1>>

declare

rno number (5);

beginrno:=&rno;

select * fr om std where rno=block1.rno;

<<block2>>

begin

««««

end;

end;

8/4/2019 PLnew


<<o>>

declare

i number (2):=1;begin

dbms_ output.put_line(i);

<<ii>>

declare

i number (2):=10 ;

begin

dbms_ output.put_line(o.i);

dbms_ output.put_line(ii.i);

dbms_ output.put_line(i);

end;

end;

8/4/2019 PLnew


Oracle tractions

Transaction is series of operation perf orm on

DB. Following events take place

connecting to oracle

committing changes to DB

r o

llbackdisconnecting fr om DB

8/4/2019 PLnew


transaction has four fundamental

properties, known as ACID properties:

Atomicity Transactions are committed or rolledback as a group, and are atomic, meaning that allSQL statements contained in a transaction areconsidered to be a single indivisible unit.

Consistency Transactions ensure that the databasestate remains consistent, meaning that thedatabase starts at one consistent state and ends inanother consistent state when the transactionfinishes.

Isolation Separate transactions should appear torun without interfering with each other.

Durability Once a transaction has been committed,the database changes are preserved.

8/4/2019 PLnew


Commit

Ends the transaction and make the changes

permanent.

Commit;

8/4/2019 PLnew


Rollback

Remove the changes made during a

transaction.

r ollback [to [savepoint] <save point name>]

8/4/2019 PLnew


Creating save point

Savepoint <save point name>;

8/4/2019 PLnew


Rollback without Savepoint

clause

Ends the transaction.

Undoes all the changes.

Erase all save point in that transaction.

Release the transaction lock.

8/4/2019 PLnew


Rollback with Savepoint

A predetermined portion of transaction is r oll

backed.

Release the transaction lock.

8/4/2019 PLnew


Example

Declare

no number (5);

Begin

no:=&no;savepoint no _update;

update emp set sal=sal+no;if no>5000 then

r ollback to savepoint no _update;end if;

commit;

End;

8/4/2019 PLnew


Flashbacks

If you mistakenly commit changes and you

want to view r ows as they originally were, you

can use a query flashback .

EXECUTE DBMS_ FLASHB ACK.EN ABLE_A

T_TIME(SYSDATE - 10 / 1440);

8/4/2019 PLnew


Record data type

Declare

type stdrec is record(

rno number (3),

namevarchar2(10),per number (4,2));

s1 stdrec;

begin

s1.rno:=10;

s1.name:=µxyz¶;

s1.per:=68;

end;

8/4/2019 PLnew


Show file content

declarefid UTL_ FILE.FILE_TYPE := UTL_ FILE.FOPEN (loc, file, 'R');line VARCHAR2(2000);

BEGINDBMS_ OUTPUT.PUT_LINE (file);LOOPUTL_ FILE.GET_LINE (fid, line);DBMS_ OUTPUT.PUT_LINE (line);

exit when no _data_f

ound;END LOOP;

end;

8/4/2019 PLnew


Writing on a file

declarefid UTL _FILE.FILE_TYPE : = UTL _FILE.FOPEN (loc, file, µw');v VARCHAR2(2000);BEGIN

v:=µvdvfdbfbd¶;

UTL _FILE.PUT _LINE (fid, v);UTL _FILE.FCLOSE (fid);

end;

8/4/2019 PLnew


Cursor

The oracle engine uses a work area f or

internal pr ocessing in order to execute an sql

statement.

Active data set.

8/4/2019 PLnew


Type of cursor

Implicit cursor.

Explicit cursor.

8/4/2019 PLnew


Implicit and explicit cursor has

4 attribute

%ISOPEN

%FOUND

%NOT FOUND

%ROWCOUNT

8/4/2019 PLnew


IMPLICIT CURSOR.

Oracle engine open this cursor and manage

it.

The value of this cursor always refer to most

recently executed sql statement.

8/4/2019 PLnew


Example

Begin

update acct set bal=bal+5000 where

acno

=141;if sql%notf ound then

dbms_ output.put_line(µerr or in updation¶);

end if;

End;

8/4/2019 PLnew


For loop with implicit cursor

Begin

for cur1 in(select rno, name, per from std where per >=60)

loop

insert into std1 values(cur1.rno, cur1.name, cur1.per);end loop;

end;

/

8/4/2019 PLnew


Explicit cursor

� Create a

named

SQL area

DECLAREDECLARE

� Identify

the active

set

OPENOPEN

� Load the

current

row into

variables

FETCHFETCH

� Release

the active

set

CLOSECLOSE

Yes

� Test for

existing

rows

EMPTY?EMPTY?

� Return toFETCH if

rows are

found

No

1. Open the cursor.

8/4/2019 PLnew


Cursor

pointer

p

2. Fetch a row using the cursor.

Cursor

pointer

Continue until empty.

Cursor

pointer

3. Close the cursor.

8/4/2019 PLnew


Cursor declaration

A cursor is defined in declarative part of a

pl/sql block.

Cursor <cursor name> is select statement;

8/4/2019 PLnew


Opening a cursor

Open <cursor name>;

8/4/2019 PLnew


Fetching record from cursor

Fetch <cursor name> into var1, var2,««;

8/4/2019 PLnew


Closing cursor

Close <cursor name>;

8/4/2019 PLnew


Explicit cursor attributes

%f ound

%notf ound

%isopen

%r owcount

8/4/2019 PLnew


Example

DECLARE

v_empno employees.employee_id%TYPE;

v_ename employees.last_name%TYPE;

CURSOR emp_cursor IS

SELECT employee_id, last_name

FROM employees;BEGIN

OPEN emp_cursor;

LOOP

FETCH emp_cursor INTO v_empno, v_ename;

EXIT WHEN emp_cursor%ROWCOUNT > 10 OR

emp_cursor%NOTFOUND;

DBMS _OUTPUT.PUT _LINE (TO_CHAR(v_empno)

||' '|| v_ename);

END LOOP;

CLOSE emp_cursor;

END ;

8/4/2019 PLnew


Cursor example

Declare

cursor c1 is

select name, sal from emp;

name emp.name%type;

sal emp.sal%type;Begin

open c1;

loop

fetch c1 into name, sal;

exit when c1%notfound;dbms_output.put_line(name||¶ µ||to_char(sal));

end loop;

End;

8/4/2019 PLnew


%rowtype

Declare

cursor c78 is select rno, name, per from std1 where namelike µa%¶;

varcur c78 %rowtype;

begin

open c78;

fetch c78 into varcur;

while c78%found loop

dbms_output.put_line(varcur.rno ||¶ µ|| varcur.per);fetch c78 into varcur;

end loop;

end;

/

8/4/2019 PLnew


Illegal fetch

Cursor c1 is select * fr om std;

Fetch c1 into

b_rno, b_per; (err

or)

8/4/2019 PLnew


Cursor using for loop

For <variable> in <cursor name>

Here f or l

oop

variable is aut

omaticallycreated of %r owtype.

C f l t ti ll

8/4/2019 PLnew


Cursor for loop automatically

do the following

Implicitly declared its loop index as a

%r owtype record.

Open a cursor.

Fetch a r ow fr om cursor f or each loop

iteration.

Closes the cursor when all the r ows have

been pr ocessed.

8/4/2019 PLnew


Example

Declare

cursor c2 is select eid, sal fr om emp wheredeptno=20;

Beginf or emp_rec in c2

loop

update emp set sal=emp_rec.sal+1000;

end loop;commit;

End;

8/4/2019 PLnew


Parameterized cursor

Cursor <cur name> (var data type,«)

is <select statement>;

Open <cur name> (value/variable/expression;)

8/4/2019 PLnew


Example

Declare

cursor c_emp (No NUMBER) is select count(*) fromemployee where deptno = No;

deptNo

employee.deptn

o%type:=10;countEmp NUMBER;

Beginopen c_emp (deptNo);fetch c_emp into countEmp;

close c_emp;dbms_ output.put_line(to _char (countEmp));

End;

/

8/4/2019 PLnew


Cursor for updation

Cursor c1 is select name, per fr om std f or

update;

Any changes are not reflected to DB if update

clause is not specified.

8/4/2019 PLnew


Fetching across commit

Commit must be used after all fetch

statement in case of update cursor. If used

inside loop than it will release all the locks

and any further fetch will fail.

8/4/2019 PLnew


Reference cursor SQL> declare

2 c1 sys_refcursor;3 abc a%rowtype;

4 begin

5 open c1 for select no from a ;

6 loop

7 fetch c1 into abc;

8 exit when c1%notfound;

9 dbms_output.put_line(abc.no);

10 end loop;

11 close c1;

12 end;

13 /1

11

111

1111

PL/S L rocedure successfull com leted.

8/4/2019 PLnew


Creating table variable

Type tab1 is table of std.per %type;

Type tab2 is table of std%r owtype;

Type tab3 is table of number index bybinary_integer;

Type tab4 is table of date index bybinary_integer;

8/4/2019 PLnew


ExampleDeclare

type notab is table of number index by binary_integer;

v1 notab;

Begin

f or v2 in 1..10 loop

v1(v2):=v2*10;

end loop;

Dbms_ output.put_line(µtable elements are);

f o

r v

2 in 1..10 loo

pDbms_ output.put_line(v1(v2));

end loop;

End;

/

8/4/2019 PLnew


Varray

Type <var> is varray (size) of type [not null];

8/4/2019 PLnew


Example

DeclareType no is varray (20) of number (3);

V1 no;

V2 no:= no(11,22);

V3 no:=no (null);

Begin

if v3 is null and v1 is null then

dbms_ output.put_line(µnull¶);

End if;

V2(1):=& V2(1);V2(2):=& V2(2);

End;

/

8/4/2019 PLnew


Pl /sql security

For concurrency contr ol locking method is

used.

Implicit locking

Explicit locking

8/4/2019 PLnew


Type of locks

Shared lock

Exclusive l

ock

8/4/2019 PLnew


Level of lock

Row level

Page level

Table level

8/4/2019 PLnew


Explicit locking

Client a> select * fr om std where rno=10 f or

update;

Record will be locked and released when

commit or r ollback is fired.

Client b> select * fr om std where rno=10 f or

update;

Client a> select * fr om std where rno=10 f or update nowait;

8/4/2019 PLnew


Lock table

Lock table <tn1> [,<tn2>,«.]

in {r ow share | r ow exclusive | share update |

share | share r ow exclusive | exclusive }

[nowait]

8/4/2019 PLnew


Releasing lock

Commit

Rollback

Rollback to save point

8/4/2019 PLnew


Deadlock

Transaction 1

begin

update std set per=90 where rno=10;

update std set per=50 where rno=20;end;

Transaction 2

begin

update std set per=50 where rno=20;update std set per=90 where rno=10;

end;

8/4/2019 PLnew


Exception handling

Exception condition

Exception handler

Named exception(15-20)

Numbered exception(20000)

Default exception handling

8/4/2019 PLnew


Error type

Err or type reported by handled by

Compile time pl/sql compiler compiler report

err or

Runtime pl/sql runtime exception

engine handler

8/4/2019 PLnew


Syntax

Exception

when <exception name> then

<user specified action>

8/4/2019 PLnew


Named exception

DUP _VAL_ ON _ INDEX

LOGIN _DENINED

NO _DATA_ FO

UND

PROGRAM _ERROR

TIMEOUT_ ON _RESOURCE

TOO _ M ANY _ROWS

VALUE_ERROR

OTHERS

TIMEOUT ON RESOURCE

8/4/2019 PLnew


TIMEOUT_ ON _RESOURCE

TRANSACTION _ B ACKED_ OUT

INVALID_CURSOR ZERO _DIVIDE

INVALID_ NUMBER (eg char to number)

STORAGE_ERROR

VALUE_ERROR (eg conversion, truncation err or)

ROWTYPE_ MISM ATCH

CURSOR_ALREADY _ OPEN

COLLECTION _ IS_ NULL SUBSCRIPT_ OUTSIDE_LIMIT

SUBSCRIPT_ BEYOND_COUNT

CASE_ NOT_ FOUND

8/4/2019 PLnew


EXAMPLE

Declarev1 std.per % type;

Begin

select per into v1 fr

om std where rn

o=10;

dbms_ output.put_line(v1);

Exception

when no _data_f

ound then

dbms_ output.put_line(µno record f ound¶);

End;

8/4/2019 PLnew


User named exception handlers

Declare

<exception name> exception;

pragma exception_init(<exception name>,<error no>);

Begin

.

.

.

Exception

when <exception name> then.

.

.

End

E l

8/4/2019 PLnew


Example

Declarev1 std.per % type;

v2 std.rno %type;

resource_bsy exception;

pragma exception_init(resourse_bsy,-00054);

Begin

update std set per=&v1 where rno=&v2;

Exceptio

nwhen resource_bsy then

dbms_ output.put_line(µr ow is used by other¶);

End;

User defined exception handling

8/4/2019 PLnew


p g

for business rule validations

Declare<exception name> exception;

Begin

.

.if <condition> then

raise <exception name>;

end if;

Exception

when<exception name> then

<action>

End;

Example

8/4/2019 PLnew


ExampleDeclare

r std.rno %type;

n std.name % type;

p std. per %type;

temp number (2);

e1 exception;

Begin

r:=&r;

n:=&n; p:=&p;

Select count(rno) into temp from std where rno =r;

If temp = 0 then

insert into std values(r,n,p);

else

raise e1;

end if;

Exception

when e1 then

dbms _ output. put _ line(µerror in insertion¶);

End;

Control passing to exception

8/4/2019 PLnew


Control passing to exception

handler

Declare

e1 exception;

Begin

««raise e1;

««

Exception

when e1 then«««

End;

SQL> BEGIN

8/4/2019 PLnew


DBMS_ OUTPUT.PUT_LINE(1 / 0);EXCEPTION

WHEN OTHERS THENDBMS_ OUTPUT.PUT_LINE(' An exception occu

rred');WHEN ZERO _DIVIDE THEN

DBMS_ OUTPUT.PUT_LINE('Division by zer o');

END;/WHEN OTHERS THEN

*ERROR at line 4:ORA-06550: line 4, column 4:PLS-00370: OTHERS handler must be last among the exception handlers of a block

8/4/2019 PLnew


Sqlcode and sqlerrm

Inside others handler it is often useful to

know which oracle err or raise exception.

Sqlcode returns current err or code.

Sqlerrm return err or message text.

Example

8/4/2019 PLnew


Example

Declarev1 std.rno % type;

Begin

select rno into v1 fr om std;

Exception

when others then

dbms_ output.put_line (sqlcode || sqlerrm);

End;

8/4/2019 PLnew


Raise application error

Raise_application_err or (no, msg );

No

can be between -20000 and -20999

Msg can be 512 characters

Example

8/4/2019 PLnew


ExampleDeclare

temp number (5);

Begin

select count (rno) into temp fr om std;

if temp <1 then

raise_application_err or (-20001,¶no student

data available¶);

end if;End;

8/4/2019 PLnew


Error propagation

If current block has a handler f or exception

than execute it and complete the block

successfully. Later on contr ol is passed to

enclosing block.

If there is no handler f or the exception than

pr opagate it to the enclosing block which will

handler it if handler is define f or thatexception otherwise default exception

handler will handle the exception.

Declare

8/4/2019 PLnew


Declare

a exception;

Begin

Begin

raise a;

Exception

when a then

«««.

End;

End;

Exception a is

raised in subblock

Exception a is

handled in sub

block

Declare

8/4/2019 PLnew


a exception;

b exception;

Begin

Begin

raise b;

Exception

when a then

«««.

End;

Exception

when b then

«««

End;

Exception b is

raised in subblock

No handler for

b in sub block

Exception b ispropagated to

outer block and

handled there

Declare

a exception;

8/4/2019 PLnew


b exception;

c exception;

Begin

Begin

raise c;

Exception

when a then

«««.

End;

Exception

when b then

«««

End;

Exception c is

raised in subblock

No handler for

c in sub block

Exception c is

propagated to

outer block butthere is no

handler

Exception will be

handled by

default handler

8/4/2019 PLnew


Declare

num number(3):=µabc¶;

Begin

.

.

.

.

Exception

when others then

.

.

End;

Value

error

Even others handler

exist it is not executed

Block¶s value error

exception will be

handled by default

handler

8/4/2019 PLnew


Begin

Declare

num number(3):=µabc¶;

Begin

«««

Exception

when others then

««..

End;

Exception

when others then

.

.

End;

Value

error

Even others handler

exist in inner block it isnot executed

Outer block

exception handler

will handle it

Declare

8/4/2019 PLnew


a exception;

b exception;

Begin

raise a;

Exception

when a then

raise b;

when b then

«..

End;

Exception

a is raised

Exception b is

raised

Even thoughthere is a handler

for b here, it is

not executed. The

exception is

propagated out of

block

Block completes

unsuccessfully

with unhandled

exception b

Begin

Exception a is

8/4/2019 PLnew


Declare

a exception;

b exception;

Begin

raise a;

Exception

when a then

raise b;

when b then

«««..

End;

Exception

when b then

«««

End;

Exception a is

raised

Exception is

handled and b is

raised

Even though handler

for b exist still it willpropagate out of block

Exception b is

handled here

Exception

8/4/2019 PLnew


Declare

a exception;

Begin

raise a;

Exception

when a then

««««.

raise;

End;

Exception

a is raised

Exception a is

handled

Same exception is

raised again

Exception is

propagated out of the

block

8/4/2019 PLnew


Procedure and functions

These are set of sql and pl/sql statement that

perf orm specific task.

Consist of 3 parts

declarative part

executable part

optional exception handling part

Where procedure and function

8/4/2019 PLnew


are saved

Stored in oracle database

Invoked by any pl/sql block

Bef ore saving pr ocedure or function oracle

engine parses and compiles it.

If err or occur during compilation invalid

pr ocedure or function is created.

8/4/2019 PLnew


Select * fr om user_err ors;

8/4/2019 PLnew


Steps of execution

Verify user access

Verify pr ocedure or function validity

Executes pr ocedure or function

8/4/2019 PLnew


Advantages

Security

Perf ormance

Memory allocation

Pr oductivity

Integrity

8/4/2019 PLnew


Procedure vs. functions

Function can return a value back to calling point. A

function can return only one value to calling point.

By defining multiple out parameter in pr oceduremultiple values can be passed to calling point.

A pr ocedure call is a pl/sql statement while function

call is a part of an expression.

8/4/2019 PLnew


Syntax of procedure

Create or replace procedure [schema.]<name>

(<argument>{in,out,in out}<data type>,«){is,as}

<variable constant declaration>;

Begin

««..

Exception

«««

End;

8/4/2019 PLnew


Syntax of function

Create or replace function [schema.]<name>

(<argument>in<data type>,«)

R eturn <data type> {is,as}

<variable constant declaration>;

Begin

««..

Exception

«««

End;

8/4/2019 PLnew


Return statement

There can be more than one return statement

in a function although only one of them will be

executed.

It will be an err or if there is no return

statement in a function.

8/4/2019 PLnew


Example

Create or replace function f1 (sal1 in number)

Return number is

Temp number (5);

Begin

select count (eid) into temp fr om emp where

sal > sal1;

return temp;

End;

Declare

8/4/2019 PLnew


v1 number (3);

Beginv1:=&v1;

v1:=f1(v1);

dbms_ output.put_line(v1);End;

Example procedure

8/4/2019 PLnew


Example procedure

Create or replace pr ocedure p1(rnoo innumber, namee in varchar2, perr number) is

Begin

insert into

stdvalues(rn

oo, namee, perr);

End;

Declare

8/4/2019 PLnew


namee std.name %type:=µabc¶;

rnoo std.rno %type:=10;perr std.per %type:=70;

Begin

p1(rnoo, namee, perr);End;

Deleting stored procedure or

f ti

8/4/2019 PLnew


function

Dr op pr ocedure <name>;

Dr op function <name>;

P t f d

8/4/2019 PLnew


Parameter of procedure

Name [mode] data_type:=default value;

M d

8/4/2019 PLnew


Mode

In

Out

In out

Passing parameter by value and by reference

I

8/4/2019 PLnew


In

The value of actual parameter is passed into

pr ocedure when pr ocedure is invoked. Inside

pr ocedure f ormal parameter act like pl/sql

constraint and cant be changed.

O t

8/4/2019 PLnew


Out

Any value actual parameter has when

pr ocedure is called is ignored. Inside the

pr ocedure f ormal parameter act like

un-initialized pl/sql variable and has nullvalue. When pr ocedure finishes and contr ol

return to calling envir onment content of

f ormal parameter are assigned to actual

parameter.

I t

8/4/2019 PLnew


In out

This is combination of in out. The value of

actual parameter is passed into pr ocedure

when pr ocedure is invoked. Inside pr ocedure

f ormal parameter act like an initializedvariable and can be read and written. When

the pr ocedure finishes contr ol return to calling

envir onment and content of f ormal parameter

are assigned to actual parameter.

E l

8/4/2019 PLnew


Example

create or replace pr ocedure p1

( v1 in number, v2 out number, v3 in out number) is

lv1 number:=0;

beginlv1:=v1; /* v1:=4 ; err or */

v2:=4; /* lv1:=v2; err or */

v3:=v3+v3;

end;

SQL> declare

2 v11 number:=11;

8/4/2019 PLnew


2 v11 number:=11;

3 v22 number:=22;

4 v33 number:=33;

5 begin

6 p1(v11,v22,v33);

7 dbms_ output.put_line(v11||¶ µ ||v22||¶ µ||v33);8 end;

9 /

11 4 66

PL/SQL pr ocedure successfully completed.

% t pe proced re parameter

8/4/2019 PLnew


% type procedure parameter

Create or replace pr ocedure p1

(vrno std.rno%type,«««)is

Exception inside subprogram

8/4/2019 PLnew


Exception inside subprogram

If pr ocedure or function has no exception

handler f or the exception condition than

contr ol immediately passes out to the calling

pr ogram i.e. calling envir onment inaccordance with exception pr opagation rule.

Package

8/4/2019 PLnew


Package

Package is oracle object which hold other objects within it.

Allow efficient organization of commercial

application Allow granting of privileges efficiently

Enable overloading of function and pr ocedure

Impr oves perf ormance by loading multipleobjects into memory.

Pr omote reuse of code.

Package specification

8/4/2019 PLnew


Package specification

Name of the package

Name of the variable and data type

This declaration is local to the DB and local to

the package.

Package declaration

8/4/2019 PLnew


Package declaration

Create package pack1 is

function f1(v1 in varchar2) return number;

pr ocedure p1(v2 in varchar2, v3 in varchar2);

End pack1;

Package body

8/4/2019 PLnew


Package body

Create or replace package body pack1 as

function f1(v1 in varchar2) return number

begin

«««

exception«««

end;

pr ocedure p1(v2 in varchar2, v3 in varchar2)

begin

«««exception

«««..

end;

End pack1;

Invoking a package

8/4/2019 PLnew


Invoking a package

Verify user access.

Checks that pr ocedure is valid or not if not

than it is automatically recompiled.

The package subpr ogram is executed.

Syntax for using package

8/4/2019 PLnew


Syntax for using package

Package_name.type_name

Package_name.object_name

Package_name.subpr ogram_name

Executing package members

8/4/2019 PLnew


Executing package members

Execute pack1.p1(µgsfhd¶);

Execute pack1.p1(v22);

Call pack1.p1(v22);

Package object: private /

public

8/4/2019 PLnew


public

Any item declared within package

specification are public i.e. visible outside the

package.

All items declared inside package body are

private.

Overloading procedure and

functions

8/4/2019 PLnew


functions

Functions with same name but different

parameters are called overloaded function.

Create or replace package check isfunction ok (date1 in date) return number;

function ok (num in number) return number;

end check;

Create or replace package body check is

function ok (date1 in date) return number

8/4/2019 PLnew


begin

if date1< sysdate thenreturn 1;

else

return 0;

end if;

end;function ok (num in number) return number

begin

if num<10 then

return 0;

else

return 1;

end if;

end;

End check;

Calling

8/4/2019 PLnew


Calling

Begin

if check .ok (22) = 1 then

dbms _ output. put _ line(µnumber is greater than 10¶);

end if;

End;

Restriction

8/4/2019 PLnew


Restriction

At least one of the parameter of overloading

function or pr ocedure must differ.

Overloading pr ocedure or function cant have

same number of parameters with different

name and different mode but same data type.

8/4/2019 PLnew


Overloading functions or pr ocedures withsame parameter name , mode and data type

but different return type are not permitted.

All the overloaded modules must be defined

within same scope or block.

Trigger

8/4/2019 PLnew


Trigger

Trigger are the implicit pr ocedure that are

implicitly executed when insert, update,

delete is issued against a table.

Use of trigger

8/4/2019 PLnew


Use of trigger

A trigger can permit DML statement against a

table only if they are issued during regular

business hours.

It can be used to prevent invalid transaction.

Enf orces complex security.

It can also be used to keep track of updated

or deleted records.

Cascading trigger

8/4/2019 PLnew


Cascading trigger

When a trigger is fired sql statement inside

trigger can also fire some other trigger. This

is called cascading trigger.

Trigger vs procedure

8/4/2019 PLnew


Trigger vs. procedure

Trigger do not accept parameter whereas

pr ocedure can.

Trigger is executed implicitly by oracle engine

itself upon modification of an associated

table. To execute pr ocedure it has to be

explicitly called by user.

Trigger vs integrity constraint

8/4/2019 PLnew


Trigger vs. integrity constraint

Integrity constraint is a statement about DB

that is always true.

Trigger contain what a transaction can do i.e.

trigger do not apply to data loaded so it don't

guarantees that all the data in the table

confirms rules.

How to apply database

triggers

8/4/2019 PLnew


triggers

Triggering event or statement

Trigger restriction

Trigger action.

Type of trigger

8/4/2019 PLnew


Type of trigger

Row triggers

fired each time a r ow in the table is affected.

E.g. update statement changes multiple r owsthan trigger is fired f or each r ow.

Statement trigger

8/4/2019 PLnew


Statement trigger

Fired once on behalf of triggering statement.

Independent of number of r ows affected.

Used when pr ocessing is required which is

independent of number of r ows affected.

Before triggers

8/4/2019 PLnew


Before triggers

Trigger action are executed bef ore triggering

statement.

Bef ore trigger determine whether or not

triggering statement should be allowed to

complete.

After trigger

8/4/2019 PLnew


After trigger

Trigger action are executed after triggering

statement.

Combinations

8/4/2019 PLnew


Combinations

Bef ore statement trigger

Bef ore r ow trigger

After statement trigger

After r ow trigger

Syntax

8/4/2019 PLnew


Syntax

Create or replace trigger <name>

{before, after}

{delete, insert, update [of column«.,..]}

On <table name>

[referencing {OLD as old, NEW as new }]

[for each row [when condition]]

Declare

««

Begin««..

Exception

«««

End

Create trigger audit

after update or delete on cust

8/4/2019 PLnew


f or each r ow

DeclareOp varchar (20);

Begin

if updating then

op:=µupdate¶

Elsif deleting then

op:=µdelete¶;

End if;

Insert into cust_backup values(:old.cust_id, :old.name,:old.sal, user, sysdate);

End;

Three categories

8/4/2019 PLnew


ee catego es

DML trigger

Instead-of trigger

System trigger

DML trigger

8/4/2019 PLnew


gg

This trigger is fired by a DML statement.

DML trigger can be defined f or insert, update

or delete operation.

Instead-of trigger

8/4/2019 PLnew


gg

These triggers can be defined only on views.

Instead of trigger will be executed instead of

DML statement.

Instead of trigger must be r ow level.

Example

8/4/2019 PLnew


p

Create or replace view class as

select dept, building, r oomno fr om classes

where building=µbcom¶;

Insert into class values(µsci¶, µbe¶, 10);

Create or replace trigger classtrigger

Instead of insert on class

8/4/2019 PLnew


DeclareTemp number (3);

Begin

select count (r oomno) into temp fr om classes

where r oomno=10 and building=µbe¶;if temp=0 then

Insert into classes values(µsci¶, µbe¶, 10);

else

dbms_ output.put_line(µ insert not possible¶);

end if;

End;

System trigger

8/4/2019 PLnew


y gg

System trigger fires when a system event

such as DB startup or shut down occurs.

System trigger can also be fired on DDLstatement

Create or replace trigger logcreate

After create on schema

8/4/2019 PLnew


After create on schema

Begininsert into db_tab (user_id, object_type,

object_name, object_ owner,

createion_date) values(user, sys.dictionary_ obj_type,

sys.dictionary_ obj_name,

sys_dictionary_ obj_ owner, sysdate);End;

8/4/2019 PLnew


8/4/2019 PLnew


8/4/2019 PLnew


8/4/2019 PLnew


8/4/2019 PLnew


8/4/2019 PLnew


8/4/2019 PLnew


8/4/2019 PLnew


8/4/2019 PLnew


8/4/2019 PLnew


8/4/2019 PLnew


8/4/2019 PLnew


8/4/2019 PLnew


8/4/2019 PLnew


8/4/2019 PLnew


8/4/2019 PLnew


8/4/2019 PLnew


8/4/2019 PLnew


PLnew

Documents