Adv Plsql1

7/27/2019 Adv Plsql1

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Advanced Oracle PLSQL

programming

Advantech 1 Krishnamurthy


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Anonymous Procedure Function

[DECLARE]

BEGIN

--statements

[EXCEPTION]

END;

PROCEDURE name

IS

BEGIN

--statements

[EXCEPTION]

END;

FUNCTION name

RETURN datatype

IS

BEGIN

--statementsRETURN value;

[EXCEPTION]

END;

PL/SQL Block Structure



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Naming Conventions Advantages of proper naming

conventions: Easier to read

Understandable

Gives information about the functionality

Easier to debug

Ensures consistency



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Do not use reserved keywords as identifiers:

To list reserved keywords use data dictionary view v$reserved_words

- select keyword from v$reserved_words;

Label blocks You can give a name to a block so that you canaccess corresponding blocks variables in sub-blocks

Loop Labels - You can give a name to a loop by using a label

FOR year_number IN 1800..1995

LOOPFOR month_number IN 1 .. 12LOOP

IF year_loop.year_number = 1900 THEN ... END IF;

END LOOP month_loop;END LOOP year_loop;



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Procedures A procedure is:

A named PL/SQL block that performs a

sequence of actions and optionally returns avalue or values

Stored in the database as a schema object

Used to promote reusability andmaintainability

[CREATE [OR REPLACE]] PROCEDURE [schema.]name[(parameter[,parameter...] ) ]

[AUTHID DEFINER | CURRENT_USER] IS[declarations][PRAGMA AUTONOMOUS_TRANSACTION]BEGIN executable statements

[ EXCEPTION exception handlers]END [name];

Note : Importance of OR REPLACE to be explained



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Procedural Parameter Modes

Callingenvironment

Procedure

procedure

BEGIN

EXCEPTION

END;

IN parameter

OUT parameter

IN OUT parameter



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Any assignments made toparameters are rolledback when an exceptionis raised in the program*

Any assignments madeto parameters are rolledback when an exceptionis raised in the program*

In parametercannot bemodified in theprogram*

Actual parameter must bea variable

Actual parameter mustbe a variable

Actual parametercan be constant,expression,variable etc.,

Cannot have defaultvalue

Cannot have defaultvalue

Can have defaultvalue

Sub-program takes

in/gives out value

Sub-program gives out

value

Sub-program

takes value

Pass by valuePass by valuePass by reference

IN OUTOUTIN

Parameter modes

*example discussed in next slideAdvantech 7 Krishnamurthy


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IN parameter-variable vsal number

-exec :vsal:=1000-create or replace procedure ex(psal IN number)isbegin

psal:=500; -- illegal

update . . .end;

/OUT / IN OUT parameter

-variable vsal number-create or replace procedure ex(psal OUT number)isbegin

psal:=500; -- rolled back

select sal into psal from emp where empno=9999; -- raises excep.end;

/-exec ex(:vsal)

-print vsal(null)Advantech 8 Krishnamurthy


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The NOCOPY Parameter Mode Hint

NOCOPY is a hint to the compiler about how you would like the

PL/SQL engine to work with the data structure being passed in as anOUT or IN OUT parameter.

Parameter mode Passed by value or reference? (default)

IN By reference

OUT By value

IN OUT By value

We can infer from these definitions and rules that when a large datastructure (such as a collection, a record, or an instance of an objecttype) is passed as an OUT or IN OUT parameter, that structure will

be passed by value, and your application could experienceperformance and memory degradation as a result of all this copying.The NOCOPY hint is a way for you to attempt to avoid this.

The syntax of this feature is as follows:parameter_name OUT NOCOPY or IN OUT NOCOPY datatypeAdvantech 9 Krishnamurthy


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Matching Actual and Formal Parameters in PL/SQL

PL/SQL offers two ways to make the association between actual and

formal parameters:

Positional notation - Associate the actual parameter implicitly (byposition) with the formal parameter.

Named notation - Associate the actual parameter explicitly (byname) with the formal parameter.

It is more efficient to use this named notation method since it is self-

explanatory (what data to which parameter etc.,)

You can also include only the parameters you want or need in theparameter list.



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AUTHID [DEFINER] | CURRENT_USER

CREATE OR REPLACE PROCEDURE remove_emp(p_empno IN emp.empno%type,p_ename OUT emp.ename%type)

AUTHID CURRENT_USERIS

BEGINDELETE EMP WHERE EMPNO=p_empnoRETURNING ename INTO p_ename;IF SQL%FOUND THEN

dbms_output.put_line(sql%rowcount||' row deleted.');COMMIT;ELSE

dbms_output.put_line('0 rows deleted.');END IF;

END;



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PRAGMA AUTONOMOUS_TRANSACTION

These are independent transactions which performs commit/rollbackonly local DML changes and not main transaction. These are startedand ended by named subprograms

CREATE OR REPLACE PROCEDURE ADD_PLAYER(name VARCHAR2)

ISPRAGMA AUTONOMOUS_TRANSACTION;

BEGININSERT INTO CRICKET VALUES(NAME);

COMMIT; -- tcl command mandatory else throws runtime errorsEND;/INSERT INTO CRICKET VALUES('DRAVID');

EXEC ADD_PLAYER('SEHWAG'); -- COMMITTED

ROLLBACK; -- rolls back inserting of DRAVID record but SEHWAG isadded and committed



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Functions A function is:

A named block that must return a value

Stored in the database as a schema object Called as part of an expression or used to

provide a parameter value[CREATE [OR REPLACE]] FUNCTION [schema.]name[( parameter [, parameter ...] ) ]

RETURN return_datatype[AUTHID DEFINER | CURRENT_USER][DETERMINISTIC] [PARALLEL ENABLE ...] [PIPELINED][RESULT_CACHE [RELIES ON table_name]]

IS [declaration statements]BEGIN executable statements[EXCEPTION exception handler statements]END [ name ];



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Function: ExampleCREATE OR REPLACE FUNCTION get_maxsal_limit(

p_empno IN emp.empno%type)RETURN numberis

v_hisal salgrade.hisal%type;BEGIN

SELECT hisal INTO v_hisalFROM salgrade s,emp eWHERE sal between losal and hisaland e.empno=p_empno;RETURN v_hisal;

EXCEPTIONWHEN others THEN

RETURN null;END;

/

exec dbms_output.put_line(get_maxsal_limit(7566));



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Ways to Execute Functions

Invoke as part of a PL/SQL expression Using a host variable to obtain the result:

Using a local variable to obtain the result:

Use as a parameter to another subprogram

Use in a SQL statement (subject to restrictions)

EXECUTE dbms_output.put_line(get_maxsal_limit(7566))

select empno,ename,sal,get_maxsal_limit(empno) from emp;

VARIABLE v_hisal NUMBER

EXECUTE :v_hisal := get_maxsal_limit(7566)

DECLARE v_hisal salgrade.hisal%type;

BEGINv_hisal := get_maxsal_limit(7566); ...

END;



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Restrictions on Calling Functions

from SQL Expressions

User-defined functions that are callable from

SQL expressions must: Be stored in the database Accept only I Nparameters with valid SQL data types,

not PL/SQL-specific types

Return valid SQL data types, not PL/SQL-specific

types

When calling functions in SQL statements:

Parameters must be specified with positional notation

You must own the function or have the EXECUTE

privilege



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Restrictions on Calling Functions

from SQL Expressions

Functions called from: A SELECT statement cannot contain DML statements

An UPDATE orDELETE statement on a tableT cannot query orcontain DML on the same tableT

SQL statements cannot end transactions (that is, cannotexecute COMMI T orROLLBACKoperations)

Note: Calls to subprograms that break these restrictions

are also not allowed in the function.



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You cannot have DML in a function which are invoked usingselect statement

create or replace function del_emp(e number)return numberis

n number;

begindelete emp where empno=e;n:=sql%rowcount;return n;

end;/

SQL> select del_emp(7566) from dual;select del_emp(7566) from dual

*ERROR at line 1:ORA-14551: cannot perform a DML operation inside a query



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PL/SQL Packages: Review

PL/SQL packages:

Group logically related components:

PL/SQL types

Variables, data structures, and exceptions

Subprograms: procedures and functions

Consist of two parts:

A specification A body

Enable the Oracle server to read multiple objects

into memory simultaneously



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Components of a PL/SQL Package

Packagespecification

Packagebody

Procedure A declaration;

variable

Procedure A definition

BEGINEND;

Procedure B definition

variable

variable

Public

Private



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Creating the Package Specification

Syntax:

The OR REPLACE option drops and re-creates the packagespecification.

Variables declared in the package specification are initializedto NULL by default.

All constructs declared in a package specification are visibleto users who are granted privileges on the package.

CREATE [OR REPLACE] PACKAGEpackage_name IS|AS

public type and variable declarations

subprogram specifications

END [package_name];



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Creating the Package Body

Syntax:

The OR REPLACE option drops and re-creates the packagebody.

Identifiers defined in the package body are private and not

visible outside the package body.

All private constructs must be declared before they arereferenced.

Public constructs are visible to the package body.

CREATE [OR REPLACE] PACKAGE BODYpackage_name IS|AS

private type and variable declarationssubprogram bodies

[BEGIN initialization statements]

END [package_name];



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CURSORsWhenever you issue a SQL statement, the Oracleserver opens an area of memory in which thecommand is parsed and executed. This area iscalled a cursor.

Types of cursor's1.IMPLICIT cursor

-automatically defined by oracle-INSERT/UPDATE/DELETE-SELECT INTO statement which returns single row-Name: SQL

2.EXPLICIT cursor-user defined cursors-SELECT statement which returns zero or more rows

-Name: user-defined cursor nameAdvantech 23 Krishnamurthy


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CURSORs



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Controlling Explicit CursorsControlling Explicit Cursors

Create anamed

SQL area

DECLAREDECLARE

Identifythe active

set

OPENOPEN

Load thecurrent

row into

variables

FETCHFETCH

Releasethe active

set

CLOSECLOSEYes

Test forexisting

rows

EMPTY?EMPTY?

Return toFETCH if

rows are

found

No



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Declaring a Cursor

When you declare a cursor, you name it and associate itwith a specific query. When you declare a cursor oraclenames an area of memory in server and associates selectstatement with the cursor location.

At this stage, the query is PARSED

Parsing means

- checks for syntax (formation of SQL statement)

- checks for semantics (whether cols,tables,privileges etcexists)

CURSOR cursor_name [(parameter[, parameter]...)][RETURN return_type] IS select_statement;Ex:

cursor emp_cur isselect ename,sal,hiredate,deptno from emp wheredeptno=20;



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OPENing the Cursor

Opening the cursor executes the query and identifies theresult set, which consists of all rows that meet the querysearch criteria.

For cursors declared using the FOR UPDATE clause, the

OPEN statement also locks those rows.

OPEN cursor_name;

Ex:OPEN emp_cur;

OPEN c1(emplname, 3000);

OPEN c1(SMITH, 1500); parameterized cursors

OPEN c1(emplname, esal);



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Fetching with a Cursor

The FETCH statement retrieves the rows in the result setone at a time. Each fetch retrieves the current row andthen advances the cursor to the next row in the resultset.

FETCH cursor_name INTO var1,var2,.. or record_list;

Ex:

FETCH c1 INTO my_empno, my_ename, my_deptno;

LOOPFETCH c1 INTO my_record;

EXIT WHEN c1%NOTFOUND;-- process data recordEND LOOP;



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Closing a Cursor

The CLOSE statement disables the cursor, and the resultset becomes undefined.

Once a cursor is closed, you can reopen it. Any otheroperation on a closed cursor raises the predefined

exception INVALID_CURSOR.

CLOSE cursor_name;

Ex:

CLOSE emp_cur;



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-returns number of rows processed%ROWCOUNT

-returns TRUE if cursor is

open

-always returns FALSE

since cursor is implicitly

closed

%ISOPEN

-complements %found attribute%NOTFOUND

-returns TRUE ifLASTFETCH is successful

-returns TRUE iflaststatement is successful

%FOUND

EXPLICIT cursorIMPLICIT cursorATTRIBUTE

CURSOR attributes

- returns status of the cursor



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The FOR UPDATE Clause

Syntax:

Use explicit locking to deny access for theduration of a transaction.

Lock the rows before the update or delete.

SELECT ...

FROM ...

FOR UPDATE [OF column_reference][NOWAIT];



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The FOR UPDATE Clause

DECLARE

CURSOR empcursor ISSELECT * FROM EMP WHERE sal > 1000 for update;

rec empcursor%rowtype;newsal emp.sal%type;

BEGINOPEN empcursor;LOOP

FETCH empcursor INTO rec;EXIT WHEN empcursor%NOTFOUND;

IF rec.sal >= 3000 THENnewsal:=rec.sal*1.5;

ELSEnewsal:=rec.sal*1.2;

END IF;UPDATE EMP SET SAL=newsal WHERE EMPNO=rec.empno;END LOOP;CLOSE empcursor;COMMIT;

END;Advantech 32 Krishnamurthy

Th "WHERE CURRENT OF" l


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The "WHERE CURRENT OF" clause

The update statement within the loop uses the primarykey of the table, and is therefore a reasonably efficientindex lookup.

However, since we just fetched the row in question, whyshould we need to perform an index lookup? Shouldn't wealready know where the row is?

In fact, the second index lookup is unnecessary. PL/SQL(and the programmatic interfaces) can refer to thecurrent row selected by the cursor using the clause

"WHERE CURRENT OF cursor_name". Using this notation,PL/SQL can use the row address (ROWID) stored in thecursor structure to locate the row without an indexlookup.


WHERE CURRENT OF contd


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WHERE CURRENT OF cont dDECLARE

CURSOR empcursor IS

SELECT * FROM EMP WHERE sal > 1000 for update;rec empcursor%rowtype;newsal emp.sal%type;

BEGINOPEN empcursor;

LOOPFETCH empcursor INTO rec;EXIT WHEN empcursor%NOTFOUND;IF rec.sal >= 3000 THEN

newsal:=rec.sal*1.5;

ELSEnewsal:=rec.sal*1.2;

END IF;UPDATE EMP SET SAL=newsal WHERE CURRENT OF empcursor;

END LOOP;

CLOSE empcursor;COMMIT;

END;

The WHERE CURRENT OF clause eliminates the I/Os involved with anindex lookup and does improve the performance of the updatestatement.


CURSOR FOR loop:


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CURSOR FOR loop:

PL/SQL provides a special kind of FOR loop to process the rows

returned in an explicit CURSOR.

In a CURSOR FOR loop, a declared CURSOR is OPENed, FETCHedfrom and CLOSEed automatically when all of the rows have beprocessed.

Each iteration of the loop fetches a row from the active set into arecord, which is implicitly declared for use within the loop.

The loop is terminated automatically at the end of the iteration when

the last row was FETCHed.

FOR record_name IN cursor_name LOOP

statement1;

statement2;

. . .

END LOOP;



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Handling Exceptions

An exception is an error in PL/SQL that is

raised during program execution.

An exception can be raised:

Implicitly by the Oracle server

Explicitly by the program

An exception can be handled:

By trapping it with a handler

By propagating it to the calling environment By trapping and propagating it


Predefined Exception raised when


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Predefined Exception raised when



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Handling Exceptions

Exceptionraised

Is theexception

trapped?

yes

Execute statementsin the EXCEPTION

section.

Terminate

gracefully.

no

Terminate

abruptly.

Propagate the

exception.


Predefined Exception Handler


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Predefined Exception Handler



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Exceptions: Example

DECLAREv_ename emp.ename%type;

BEGINSELECT ename INTO v_ename FROM EMP

WHERE DEPTNO=&DEPTNO;dbms_output.put_line('Name is :'||v_ename);

EXCEPTIONWHEN no_data_found THENdbms_output.put_line('No employee in this dept');

WHEN too_many_rows THENdbms_output.put_line('Multiple rows fetched. Use cursors');

END;/


Built-in Error Functions


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SQLCODE - returns the error code of the most recently raised

exception in your block. If there is no error, SQLCODE returns 0.SQLCODE also returns 0 when you call it outside of an exceptionhandler.

Oracle maintains a stack of SQLCODE values.

Suppose, for example, that function FUNC raises the VALUE_ERRORexception (-6502). Within the exception section of FUNC, you call aprocedure PROC that raises DUP_VAL_ON_INDEX (-1). Within theexception section of PROC, SQLCODE returns -1. When control

propagates back up to the exception section of FUNC, however,SQLCODE will still return -6502. Run the sqlcode_test.sql file(available on the book's web site) to see a demonstration of thisbehavior.


SQLERRMf h h f


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SQLERRM is a function that returns the error message for aparticular error code. If you do not pass an error code to

SQLERRM, it returns the error message associated with the valuereturned by SQLCODE.

If SQLCODE is 0, SQLERRM returns this string:

ORA-0000: normal, successful completion

If SQLCODE is 1 (the generic user-defined exception error code),SQLERRM returns this string: User-defined exception

Here is an example of calling SQLERRM to return the error messagefor a particular code:

BEGINDBMS_OUTPUT.put_line (SQLERRM(-1403)); or 100

END;SQL> /ORA-01403: no data found


DBMS_UTILITY.FORMAT_ERROR_STACKThi b ilt i f ti lik SQLERRM t th


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This built-in function, like SQLERRM, returns the messageassociated with the current error (i.e., the value returned by

SQLCODE).

It differs from SQLERRM in two ways:

- Its length is not restricted; it will return the full errormessagestring.

- You cannot pass an error code number to this function

Note that even though the name of the function includes theword "stack" it doesn't return a stack of errors leading back tothe line on which the error was originally raised.


DBMS_UTILITY.FORMAT_ERROR_BACKTRACEThi f ti t f tt d t i th t di l t k f


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This function returns a formatted string that displays a stack ofprograms and line numbers leading back to the line on which the

error was originally raised.

DBMS_UTILITY.FORMAT_CALL_STACK - returns a formattedstring showing the execution call stack inside your PL/SQL

application.


ExampleCREATE OR REPLACE PROCEDURE proc1 IS


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CREATE OR REPLACE PROCEDURE proc1 ISBEGIN

DBMS_OUTPUT.put_line('running proc1');RAISE NO_DATA_FOUND;

END;/CREATE OR REPLACE PROCEDURE proc2 IS

BEGINDBMS_OUTPUT.put_line('calling proc1');proc1;

END;/

CREATE OR REPLACE PROCEDURE proc3 ISBEGIN

DBMS_OUTPUT.put_line('calling proc2');proc2;

EXCEPTION

WHEN OTHERS THENDBMS_OUTPUT.put_line('Error stack at top level:');DBMS_OUTPUT.put_line(DBMS_UTILITY.format_error_backtrace);

END;/


SQL> exec proc3;calling proc2


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calling proc2calling proc1

running proc1Error stack at top level:ORA-06512: at "SCOTT.PROC1", line 4ORA-06512: at "SCOTT.PROC2", line 4

ORA-06512: at "SCOTT.PROC3", line 4


Example


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begin

dbms_output.put_line('Outer Executable section');begin

dbms_output.put_line('Inner Executable section');raise too_many_rows;

exceptionwhen others thendbms_output.put_line('Inner Exception');dbms_output.put_line('Code:'||sqlcode||' Message:'||sqlerrm);dbms_output.put_line('Error:'||dbms_utility.format_error_stack);dbms_output.put_line('Backtrace:'||dbms_utility.format_error_backtrace);raise no_data_found;

end;exception

when others thendbms_output.put_line('Outer Exception');dbms_output.put_line('Code:'||sqlcode||' Message:'||sqlerrm);dbms_output.put_line('Error:'||dbms_utility.format_error_stack);

dbms_output.put_line('Backtrace:'||dbms_utility.format_error_backtrace);end;


Output:Outer Executable section


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Outer Executable sectionInner Executable section

Inner ExceptionCode:-1422 Message:ORA-01422: exact fetch returns more than requestednumber of rowsError:ORA-01422: exact fetch returns more than requested number of rowsBacktrace:ORA-06512: at line 5 -- displays line no

Outer ExceptionCode:100 Message:ORA-01403: no data foundORA-01422: exact fetch returns more than requested number of rowsError:ORA-01403: no data found

ORA-01422: exact fetch returns more than requested number of rowsBacktrace:ORA-06512: at line 12 -- displays line no



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Trapping User-Defined Exceptions

Declarativesection

Executablesection

Exception-handlingsection

Declare Raise Reference

Name the

exception

Explicit ly raise

the exception by

using the RAISEstatement

Handle the raised

exception

Note : Example to be discussed


DECLARE--declaring user defined exception name


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g psalary_missing exception;

v_ename emp.ename%type;v_sal emp.sal%type;BEGIN

SELECT ename,sal INTO v_ename,v_sal FROM EMP WHEREEMPNO=&EMPNO;

IF v_sal IS NULL THEN--raising user defined exception explicitlyRAISE salary_missing;

ELSEdbms_output.put_line(v_ename||' earns salary of '||v_sal);

END IF;dbms_output.put_line('Rest of the executable code ......');

EXCEPTIONWHEN no_data_found THEN

dbms_output.put_line('No employee with this id.');

WHEN salary_missing THEN-- handling user exceptiondbms_output.put_line('Salary of '||v_ename||' is NULL !!!');

WHEN others THENdbms_output.put_line('Exception:'||SQLERRM);

END;Advantech 54 Krishnamurthy

Trapping Non-Predefined Oracle


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Trapping Non Predefined Oracle

Server Errors

Declarative section

Declare

Name the

exceptionCode PRAGMA

EXCEPTION_INIT

EXCEPTION section

Handle the raised

exception

Associate Reference


PRAGMA EXCEPTION_INIT


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DECLARE

child_rows_found exception;PRAGMA EXCEPTION_INIT(child_rows_found,-2292);

BEGINDELETE DEPT WHERE DEPTNO=10;

EXCEPTIONWHEN child_rows_found THENdbms_output.put_line('Cannot delete parent record.');

WHEN others THENdbms_output.put_line('Exception:'||SQLERRM);

END;


ExampleCREATE OR REPLACE PROCEDURE add_emp(


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p_empno IN emp.empno%type,

p_deptno IN emp.deptno%type)ISBEGIN

INSERT INTO emp(empno,deptno)VALUES(p_empno,p_deptno);EXCEPTION

WHEN OTHERS THENDECLAREv_errcode PLS_inTEGER := SQLCODE;

BEGINIF v_errcode = -1 THEN

DBMS_OUTPUT.put_line('Employee already exists');RAISE;

ELSIF v_errcode = -2291 THENDBMS_OUTPUT.put_line('Invalid deptno');RAISE;

ELSERAISE;

END IF;END;

END add_emp;


The RAISE APPLICATION ERROR


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The RAISE_APPLICATION_ERROR

Procedure

Syntax:

You can use this procedure to issue user-defined error

messages from stored subprograms.

You can report errors to your application and avoid

returning unhandled exceptions.

Arguments

- error_numbermust be in the range -2000 to -20999

- error_message must be text message of 2kb max

raise_application_error (error_number,

message[, {TRUE | FALSE}]);


Th


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The RAISE_APPLICATION_ERROR

Procedure

Is used in two places:

Executable section

Exception section

Returns error conditions to the user in a

manner consistent with other Oracle server

errors



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Dependencies


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Dependencies

Table

View

Database trigger

Procedure

Function

Package body

Package specification

User-defined object

and collection types

Function

Package specification

Procedure

Sequence

Synonym

Table

View

User-defined object

and collection types

Referenced objectsDependent objects


Dependencies


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Dependencies

View orprocedure

Direct

dependency

Referenced

Indirectdependency

Direct

dependency

Dependent

Table

Referenced

xxxxxxxxxxxxxxvvvvvvvvvvvvvv

xxxxxxxxxxxxxx

vvvvvvvvvvvvvv

xxxxxxxxxxxxxx

vvvvvvvvvvvvvv

xxxxxxxxxxxxxx

vvvvvvvvvvvvvv

xxxxxxxxxxxxxx

vvvvvvvvvvvvvv

Procedure

Dependent


Dependency Management

- Another important phase of PL/SQL compilation and execution is


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- Another important phase of PL/SQL compilation and execution is

the checking of program dependencies.- A dependency (in PL/SQL) is a reference from a stored program tosome Oracle object outside the program.

- Server-based PL/SQL programs can have dependencies on tables,

views, types, procedures, functions, sequences, synonyms, orpackage specifications, but not on package bodies or type bodies.

Oracle's basic dependency objective for PL/SQL is

Do not allow a program to run if any of the objects on which itdepends have changed since it was compiled.

Note: most of dependency management happens automatically,from the tracking of dependencies to the recompilation required tokeep everything synchronized.


Dependencies in PL/SQL

A simple illustration:


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A simple illustration:

I have a package epkg which contains procedures, functions, recordtypes, collections etc related to emp table. Description is as shown


To view data dictionary information regarding the same I would useuser_objects and user_dependencies


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Oracle has used its DIANA to determine a list of other objects that

EPKG needs in order to compile successfully.


Dependency graph of EPKG package


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standardPACKAGE

dbms_standardPACKAGE

dbms_outputPACKAGE

epkg BODY epkg SPEC

emp TABLE


Let us find out which objects depends on EMP table and when wemodify structure of EMP table you can observe the dependent objectsstatus


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status


You can use deptree procedure to view the dependency tree.

Run following script in SYS schema


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C:\app\Administrator\product\11.1.0\db_1\RDBMS\ADMIN\utldtree.sql

SQL> EXEC DEPTREE_FILL('TABLE', 'SCOTT', 'EMP');

SQL> SELECT * FROM IDEPTREE;

DEPENDENCIES-----------------------------------------------------------------------

PACKAGE SCOTT.EPKGCURSOR ."LOCK TABLE "EMP" IN ROW EXCLUSIVE MODE NOWAIT "

PACKAGE BODY SCOTT.EPKGPROCEDURE SCOTT.RAISE_SALARYPACKAGE BODY SCOTT.EPKG

TABLE SCOTT.EMP

Note : Using packages in your design can break the cycle of

dependencies and recompilations.


Healing InvalidsIn any event, no PL/SQL program marked as invalid will run until asuccessful recompilation restores its validity There are at least three


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successful recompilation restores its validity. There are at least three

ways that can happen:

By hand - Using an explicit ALTER command to recompile thepackage

By script - Using a program that looks for invalid packages andissues the ALTER commands for you

Automatically - Relying on Oracle's built-in recompilation rules


Recompiling by handThe "by hand" method is simple, but it can be tedious.


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ALTER PACKAGE epkg COMPILE BODY;ALTER PROCEDURE raise_salary COMPILE;

Recompiling by scriptVarious scripts exist that can help you reduce the tedium of theserecompilations. Note that these must be run while logged in to thedatabase as SYSDBA.

utlip.sql - Invalidates and recompiles all PL/SQL code and views

in the entire database.

utlrp.sql - Recompiles all of the invalid objects in serial and isappropriate for single-processor hardware.

utlrcmp.sql - Like utlrp.sql, recompiles all invalid objects, but inparallel


Automatic recompilation

Automatic recompilation, is simpler, but it isn't without drawbacks.


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If you merely execute one of the programs implemented in the EPKGpackage body, Oracle will recompile it just prior to execution.

Production environments are likely to have strict policies on whenyou can and cannot recompile programs. That's because installing a

new version of a PL/SQL program can force a lot of recompilation andcan have disastrous side effects on programs currently running.

You will probably want to run a script similar to utlrp.sqlto find andrecompile all invalid objects. Your DBA should help you schedule an

upgrade procedure, which should include running a recompilationscript.

Aside from a potentially unscheduled drain on performance, thebiggest drawback to Oracle's automatic recompilation feature is that

it can interfere with packages that are currently running.

This happens because automatically recompiling a package that iscurrently running invalidates the package.


Automatic recompilation ..

Not only that, Oracle shares the program's bytecode among differentsessions so this in alidation affects not j st the session that


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sessions, so this invalidation affects not just the session thattriggered the recompilation, but every Oracle session that hasinstantiated the package! Consequences of this devastation includethe following:

- Executions terminate with an ORA-04068 error

- All public and private package variables assume their defaultvalues; if you haven't supplied an explicit default value, it will revertto NULL. This effect applies to any package that the session hasinstantiated, not just the one that's getting recompiled. So, if youwere in the middle of any computations that assign values topackage variables, you will lose the contents of those variables.

- DBMS_OUTPUT stops working. Well, not really, but if you hadpreviously enabled it, Oracle will disable it. This occurs because itson/off switch is really a package variable, and resetting the packagestate causes this variable to revert to its default, which is off.


Remote Dependencies

Server-based PL/SQL immediately becomes invalid whenever there'sa change in a local object on which it depends However if it depends


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a change in a local object on which it depends. However, if it dependson an object on a different computer and that object changes, Oracledoes not attempt to invalidate the calling PL/SQL program in realtime. Instead, Oracle defers the checking until runtime.

Here is a program that has a remote dependency on the procedurerecompute_prices which lives across the database linkfindat.ldn.world:

PROCEDURE synch_em_up (tax_site_in IN VARCHAR2,since_in IN DATE)

ISBEGIN

IF tax_site_in = 'LONDON' [email protected](cutoff_time => since_in);

END IF;.


If you recompile the remote procedure and some time later try to runsynch_em_up, you are likely to get an ORA-04062 error withaccompanying text such as timestamp (or signature) of package


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"SCOTT.recompute_prices" has been changed.

If your call is still legal, Oracle will recompile synch_em_up, and if itsucceeds, its next invocation should run without error.

To understand Oracle's remote procedure call behavior, you need toknow that the PL/SQL compiler always stores two kinds ofinformation about each referenced remote procedure: its timestampand its signature:

timestamp - The most recent date and time (down to the second)when an object's specification was reconstructed, as given by theTIMESTAMP (date datatype) column in the USER_OBJECTS view.

For PL/SQL programs, this is not necessarily the same as the mostrecent compilation time because it's possible to recompile an objectwithout reconstructing its specification.


SignatureA footprint of the actual shape of the object's specification.


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Signature information includes the object's name and theordering, datatype family, and mode of each parameter.

So when I compiled synch_em_up, Oracle retrieved both thetimestamp and the signature of the remote procedure called

recomputed_prices, and stored a representation of them with thebytecode of synch_em_up.

How do you suppose Oracle uses this information at runtime?

The model is simple: it uses either the timestamp or the signature,depending on the current value of the parameterREMOTE_DEPENDENCIES_MODE.

If that timestamp or signature information, which is stored in thelocal program's bytecode, doesn't match the actual value of theremote procedure at runtime, you get the ORA-04062 error.


Oracle's default remote dependency mode is the timestamp method,but this setting can sometimes cause unnecessary recompilations.


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The DBA can change the system-wide setting via the databaseinitialization file or an ALTER SYSTEM command; an applicationdeveloper can set it for the current session using the followingcommand:

ALTER SESSION SET REMOTE_DEPENDENCIES_MODE = SIGNATURE;


Using Oracle-Supplied Packages


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Oracle-supplied packages: Are provided with the Oracle server

Extend the functionality of the database

Enable access to certain SQL features that are normallyrestricted for PL/SQL

For example, the DBMS_OUTPUT package wasoriginally designed to debug PL/SQL programs.


Some of the Oracle-Supplied Packages


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pp g

Here is an abbreviated list of some Oracle-

supplied packages:

DBMS_ALERT DBMS_LOCK

DBMS_SESSI ON

DBMS_OUTPUT HTP

UTL_FI LE

UTL_MAI L DBMS_SCHEDULER


DBMS_OUTPUT Package


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The DBMS_OUTPUT package enables you to send

messages from stored subprograms and triggers.

PUT and PUT_LI NE place text in the buffer. GET_LI NE and GET_LI NES read the buffer.

Use SET SERVEROUTPUT ON to display messages inSQL*Plus. (The default is OFF.)

PUT_LINE

GET_LINE

PUTNEW_LINE

GET_LINES

SET SERVEROUT ON [SIZE n]

EXEC procBuffer

Output


UTL_FILE Package


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The UTL_FI LE package extends PL/SQL programs to

read and write operating system text files.

It provides a restricted version of operating system stream fileI/O for text files.

It can access files in operating system directories defined by aCREATE DI RECTORY statement.

EXEC proc

O/S fileUTL_FILE

CREATE DIRECTORY

my_dir AS '/dir'


UTL_FILE package


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DBA configuration

connect system/ as sysdba

CREATE OR REPLACE DIRECTORY FILE_DIR AS 'C:\TEMP_FILES';

GRANT READ,WRITE ON DIRECTORY FILE_DIR TO PUBLIC;

CONNECT scott/tiger


writing emp table data into filecreate or replace procedure write_emp(

path in varchar2,


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filename in varchar2)is

output_file utl_file.file_type;cursor empcursor IS

SELECT empno,ename,sal FROM EMP;

beginoutput_file := utl_file.fopen (PATH,FILENAME, 'w');for erec in empcursor looputl_file.put_line(output_file,

erec.empno||','||erec.ename||','||erec.sal);end loop;utl_file.fclose(output_file);

exceptionwhen others thendbms_output.put_line(SQLERRM);

end;

exec write_emp('FILE_DIR','empdata.txt');


Reading contents of a filecreate or replace procedure read_file(

path in varchar2,filename in varchar2)


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)is

input_file utl_file.file_type;input_buffer varchar2(4000);

begininput_file := utl_file.fopen (path,filename,'R');dbms_output.put_line('Output:');loop

utl_file.get_line (input_file, input_buffer);dbms_output.put_line(input_buffer);

end loop;utl_file.fclose(input_file);

exceptionwhen no_data_found then

null;when others then

dbms_output.put_line(SQLERRM);end;

/exec read_file('FILE_DIR','empdata.txt');


Advanced Cursor Concepts

Cursor Variables and REF CURSORs


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A cursor variable is a variable that points to orreferences an underlying cursor.

Unlike an explicit cursor, which names the PL/SQL work

area for the result set, a cursor variable is a reference tothat work area.

Explicit and implicit cursors are staticin that they are

tied to specific queries.

The cursor variable can be opened for any query, evenfor different queries within a single program execution.


The most important benefit of the cursor variable is that it provides amechanism for passing results of queries (the rows returned by fetchesagainst a cursor) between different PL/SQL programs even between


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client and server PL/SQL programs.


It is important to distinguish between declaring a cursor variable andcreating an actual cursor object the result set identified by the cursorSQL statement.


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A constant is nothing more than a value, whereas a variable points to itsvalue. Similarly, a static cursor acts as a constant, whereas a cursorvariable references or points to a cursor object.

These distinctions are shown in figure. Notice that two different cursorvariables in different programs are both referring to the same cursorobject.


Cursor Variables REF CURSORCursor variables are like C pointers, which hold thememory location (address) of some item instead of the

lf


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item itself.

A REF CURSOR is basically a data type.

A variable created based on such a data type is generallycalled a cursor variable.

A cursor variable can be associated with different queriesat run-time.

The primary advantage of using cursor variables is their

capability to pass result sets between sub programs (likestored procedures, functions, packages etc.).


Defining REF CURSOR Types

To create cursor variables, you take two steps.

Fi t d fi REF CURSOR t th d l


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First, you define a REF CURSOR type, then declare cursorvariables of that type.

You can define REF CURSOR types in any PL/SQL block,

subprogram, or package

TYPE ref_type_name IS REF CURSOR [RETURNreturn_type];

where r e f _ t y p e _ n a m e is a type specifier used insubsequent declarations of cursor variables and

r e t u r n _ t y p e must represent a record or a row in a

database table.

Then declare variable ofref_type_name


SYS_REFCURSOR weak reference type

Oracle has pre-defined ref cursor type in standard package usingwhich you can declare a variable.


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create or replace procedure emp_refcur(cur_var out sys_refcursor)isbegin

open cur_var for select * from emp;end;/SQL> variable e_curvar refcursor

SQL> exec emp_refcur(:e_curvar)

SQL> print e_curvar


Dynamic Queries With REF CURSOR's

Oracle supports dynamic queries via the OPEN FOR USINGstatement.


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A string literal or string variable is supplied in the OPEN FOR USINGstatement to the SELECT command.

OPEN name FOR dynamic_string[ USING bind_arg [, bind_arg_2 ]...];

name is the identifier of a previously declared cursor variable.dynamic_string is a string literal or string variable containing aSELECT command.

bind_arg, bind_arg_2... are bind arguments that are used to passvariables to corresponding placeholders in the SELECT command

when the cursor variable is opened.

The placeholders are identifiers prefixed by a colon character.


Example

CREATE OR REPLACE PROCEDURE dept_query (p_deptno emp.deptno%TYPE, p_sal emp.sal%TYPE)

IS


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IS emp_refcur SYS_REFCURSOR;v_empno emp.empno%TYPE;v_ename emp.ename%TYPE;p_query_string VARCHAR2(100);

BEGINp_query_string := 'SELECT empno, ename FROM emp WHERE ' ||

'deptno = :dno AND sal >= :esal';OPEN emp_refcur FOR p_query_string USING p_deptno, p_sal;

DBMS_OUTPUT.PUT_LINE('EMPNO ENAME');DBMS_OUTPUT.PUT_LINE('----- -------');LOOP

FETCH emp_refcur INTO v_empno, v_ename;EXIT WHEN emp_refcur%NOTFOUND;

DBMS_OUTPUT.PUT_LINE(v_empno || ' ' || v_ename);END LOOP;CLOSE emp_refcur;

END;


COLLECTION

A ll ti i d d f l t ll f th


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A collection is an ordered group of elements, all of thesame type.

Each element has a unique subscript that determinesits position in the collection


Types of Collections

Associative Arrays : to hold arbitrary no of elements.I d i i b l i t bi i t h 2 iti


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Indexing is by pls_integer, binary_integer, varchar2, positiveand natural

Nested tables hold an arbitrary number of elements. They usesequential numbers as subscripts.

Varrays (variable-size arrays) hold a fixed number ofelements (although you can change the number of elements atruntime). They use sequential numbers as subscripts.

Note:A nested table & varrays are of object type and therefore

needs to first be initialized with a constructor before being used.



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Associative Arrays

Objects of the TABLE type are called INDEX BY tables.

They are modeled as database tables (but not the)


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They are modeled as database tables (but not thesame as).

Associative arrays use a primary key to provide youwith array-like access to rows.

An Associative Array:

Is similar to an array in other languages

Must contain two components:

A primary key is data that indexes the INDEX BYtable

A column of a scalar or record data type, which

stores the INDEX BY table elements

Can increase dynamically because it isunconstrained


Creating an I NDEX BY Table


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Syntax:TYPE type_name IS TABLE OF

{column_type | variable%TYPE

| table.column%TYPE} [NOT NULL]

| table.%ROWTYPE

[INDEX BY datatype];

identifier type_name;

...

TYPE ename_table_type IS TABLE OF emp.ename%TYPE

INDEX BY BINARY_INTEGER;ename_table ename_table_type;

...

Example:Declare an INDEX BY table to store names.


I NDEX BY Table Structure


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Unique identifier Column

... ...1 JONES

2 SMITH

3 KING

... ...

BI NARY_I NTEGER Scalar


Example :

DECLARETYPE IntDataTyp IS TABLE OF integer


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TYPE IntDataTyp IS TABLE OF integerINDEX BY BINARY_INTEGER;inttab IntDataTyp;

BEGINinttab(1):=10;inttab(12):=20;

inttab(25):=30;dbms_output.put_line(inttab(1)||','||inttab(12)||','||inttab(25));

END;


Note : No DML (except delete) or transactions can beimplemented on various collections

Built-in Functions and Procedures for collections


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Built in Functions and Procedures for collections

Operator Description

COUNT Returns the number of elements currently contained in the PL/SQL table.

DELETE Deletes one or more elements from the PL/SQL table.

EXISTS Returns FALSE if a reference to an element at the specified index wouldraise the NO_DATA_FOUND exception.

FIRST Returns the smallest index of the PL/SQL table for which an element is

defined.

LAST Returns the greatest index of the PL/SQL table for which an element isdefined.

NEXT Returns the smallest index of the PL/SQL table containing an element

which is greater than the specified index.

PRIOR Returns the greatest index of the PL/SQL table containing an element

which is less than the specified index.Advantech 99 Krishnamurthy

EXTEND Extends the number of elements in collection.EXTEND;a collection. Cannot be used on (extends collection by asingle element) associative arrays or other collections

that have not been initialized.


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that have not been initialized.collection.EXTEND(n);.(extends collection by nelements)collection.EXTEND(n,I); (extends collection by nelements by copying value in element indexed byI)

TRIM Removes elements from the endcollection.TRIM;.of a collection. removes a single element from end of

collectioncollection.TRIM(n);. removes n elements from end ofcollection


Deleting rows in collections

To delete specific row d l t ()


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To delete specific row.delete()

To delete all the rows

.delete

To delete range of rows

.DELETE (start_index_in IN INTEGER,end_index_in IN INTEGER);


I NDEX BY Table of Records


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DECLARE

TYPE dept_table_type IS TABLE OF dept%ROWTYPE

INDEX BY BINARY_INTEGER;

dept_table dept_table_type;

-- Each element of dept_table is a record

to refer each fielddept_table(index).field_name must be used

Define a TABLE variable with a permitted PL/SQL data type.

Declare a PL/SQL variable to hold department information.

Example:Example:


Example using CURSOR FOR LOOP

SET SERVEROUTPUT ON


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DECLARE

TYPE emp_tabtype IS TABLE OF EMP%ROWTYPE INDEX BY

BINARY_INTEGER;

EMPREC emp_tabtype;

BEGIN

for rec in (select * from emp) loop

EMPREC(rec.empno):=rec;END LOOP;

for i in EMPREC.FIRST..EMPREC.LAST LOOP

if EMPREC.exists(i) then

dbms_output.put_line(i||','||EMPREC(i).ENAME);end if;

end loop;

END;


Nested Tables

nested tables can be considered one-column database tables.

oracle stores the rows of a nested table in no particular order


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oracle stores the rows of a nested table in no particular order.

when you retrieve the nested table into a PL/SQL variable,

the rows are given consecutive subscripts starting at 1. Thatgives you array-like access to individual rows.


NESTED ARRAY vs ARRAY


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Arrays are dense and have a fixed upper bound, but nestedtables are initially dense but become sparse and are unbounded

In arrays you cannot delete elements

In nested table you can delete elements using the built-inprocedure DELETE. That might leave gaps in the index, butthe built-in function NEXT lets you iterate over any series of

subscri ts.Advantech 105 Krishnamurthy

Understanding Varrays

Items of type VARRAY are calledvarrays.

They allow you to associate a single identifier with an entire


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They allow you to associate a single identifier with an entirecollection. This association lets you manipulate the collectionas a whole and reference individual elements easily.

To reference an element, you use standard subscripting syntax

A varray has a maximum size


Defining Collection Types

You can define TABLE and VARRAY types in the

declarative part of any PL/SQL block, subprogram, or


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p y p gpackage.

Nested Tables

TYPE type_name IS TABLE OF element_type [NOT NULL]

type_name is a type specifier used later to declare collections.element_type is any PL/SQL datatype

Varrays

TYPE type_name IS {VARRAY | VARYING ARRAY}( size_limit) OF element_type [NOT NULL]type_name andelement_type are the same as for nested tablessize_limit is a positive integer


Example:DECLARE

TYPE NumList IS TABLE OF VARCHAR2(12);

nums NumList := NumList(10,20,30);BEGIN


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BEGINfor i in 1..3 loop

DBMS_OUTPUT.PUT_LINE(nums(i));end loop;nums(1):='A';nums(2):=60;

nums(3):='welcome';for i in 1..3 loopDBMS_OUTPUT.PUT_LINE(nums(i));end loop;

END;


DECLARETYPE dname_nt_type IS TABLE OF dept.dname%type;dnames dname_nt_type:=dname_nt_type();

BEGINFOR rec IN (SELECT dname from dept) LOOP


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FOR rec IN (SELECT dname from dept) LOOPdnames.EXTEND;dnames(dnames.LAST):=rec.dname;

END LOOP;FOR j IN dnames.FIRST..dnames.LAST LOOP

dbms_output.put_line(j||'-'||dnames(j));

END LOOP;END;/


Comparing Associative array, nested table & varray


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Needs

initialization(except in bulk

collect)

Does not need

initialization

initialization

Bound by size

Can hold

arbitrary no of

elements

No of

elements

Alwaysstarts from

1

Can start

from any

indexnumber

Start

index

Cannot

contain gaps

Initially dense,

after deletion

becomes

sparse

Can contain

gaps

gaps

Cannot

create

schema leveltypes

INDEX BY

clause is

used

Associative

Array

Varray

Schema

level typescan be

created

No indexby clause

Nested

Tables

Schema

types

indexcollection


Performance GainsPerformance Gains

BULK COLLECT INTO clause (ie.,BULK FETCH INTO)


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SQL

DATA

Context Switching

Performance Gains

with Bulk Bindingwith Bulk Binding

PL/SQL Engine SQL Engine

SQL Statement

ExecutorProcedural statement

Executor


The Oracle server has three execution engines: one eachfor PL/SQL, SQL, and Java.

- When running PL/SQL blocks and subprograms, thePL/SQL engine runs procedural statements but sends the


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PL/SQL engine runs procedural statements but sends theSQL statements to the SQL engine, which parses andexecutes the SQL statement and, in some cases, returnsdata to the PL/SQL engine. During execution, every SQLstatement causes a context switch between the twoengines, which results in a performance penalty.

- Performance can be improved substantially byminimizing the number of context switches required torun a particular block or subprogram. When a SQL

statement runs inside a loop that uses collection elementsas bind variables, the large number of context switchesrequired by the block can cause poor performance.



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Using FETCH cur_name BULK COLLECT INTOcollectionThis statement avoid context switching between PL/SQL

engine and SQL engine for fetching rows into colleciton


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DECLARECURSOR empcursor is select * from emp;TYPE erectabtype IS TABLE OF emp%rowtype;etab erectabtype;

BEGIN

OPEN empcursor;FETCH empcursor BULK COLLECT INTO etab;CLOSE empcursor;FOR idx IN etab.first..etab.last LOOP

dbms_output.put_line(idx||','||etab(idx).ename);END LOOP;

END;


Using SELECT col_list BULK COLLECT INTOcollection

DECLAREdeptno tab dbms sql.number table; -- inbuilt type


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p _ _ q _ ; ypename_tab dbms_sql.varchar2_table;

BEGIN

SELECT ename,deptno BULK COLLECT INTO ename_tab,deptno_tabFROM EMP WHERE SAL > 2000;FOR i IN 1..ename_tab.COUNT LOOP --or sql%rowcountdbms_output.put_line(ename_tab(i)||','||deptno_tab(i));

END LOOP;

END;/


RETURNING into arrays

DECLARE

TYPE emp_rec_type IS RECORD(empno EMP.EMPNO%TYPE,

% )


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ename EMP.ENAME%TYPE);TYPE emp_tab_type IS TABLE OF emp_rec_typeINDEX BY binary_integer;emptab emp_tab_type;

BEGINUPDATE EMP SET SAL=SAL*1.15WHERE DEPTNO=30

RETURNING empno,ename BULK COLLECT INTO emptab;FOR i IN 1..emptab.LAST LOOPdbms_output.put_line(emptab(i).empno||','||emptab(i).ename);END LOOP;

END;


INSERT with RECORD BindCREATE TABLE retired_employeesAS SELECT * FROM EMP WHERE 1=0;

DECLAREv erec emp%rowtype;


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v_erec emp%rowtype;BEGINSELECT * INTO v_erec FROM EMP WHERE EMPNO=7566;

INSERT INTO retired_employees VALUES v_erec;END;

Bulk INSERTing with a record.

DECLARETYPE emprectype IS TABLE OF emp%ROWTYPE;retirees emprectype;

BEGINSELECT * BULK COLLECT INTO retirees FROM EMP;FOR indx in retirees.first..retirees.last LOOP

INSERT INTO retired_employees VALUES retirees(indx);END LOOP;

END;


UPDATE SET ROW with RECORD Bind

Oracle gives you an easy and powerful way to update anentire row in a table from a record: the SET ROW clause.The ROW keyword is functionally equivalent to *.


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DECLARE

v_erec emp%rowtype;BEGINSELECT * INTO v_erec FROM EMP WHERE EMPNO=7566;v_erec.sal:=v_erec.sal*1.5;v_erec.job:='SR CLERK';

UPDATE emp SET ROW = v_erec WHERE empno=v_erec.empno;END;


RETURNING into a record from a DELETE statement.

DECLAREv_erec emp%ROWTYPE;BEGIN


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BEGINDELETE FROM emp WHERE empno = 7566

RETURNING empno, ename, job, mgr, hiredate, sal,comm, deptno INTO v_erec;

dbms_output.put_line('Deleted :'||v_erec.empno);END;


You can also RETURN less columnsEx - 1DECLARE

id emp.ename%TYPE;name emp.ename%TYPE;

BEGIN


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BEGINDELETE FROM emp WHERE empno = 7566RETURNING empno, ename INTO id,name;

dbms_output.put_line('Deleted :'||id||','||name);END;

Ex - 2

DECLARETYPE key_rec_type IS RECORD (id NUMBER, name VARCHAR2 (100));v_erec key_rec_type;

BEGINDELETE FROM emp WHERE empno = 7566RETURNING empno, ename INTO v_erec;dbms_output.put_line('Deleted :'||v_erec.id||','||v_erec.name);

END;


FORALL statementEx:CREATE TABLE EMPLOY IS

SELECT * FROM EMP WHERE 1=0;


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DECLARETYPE erectabtype IS TABLE OF employ%rowtype;

etab erectabtype;CURSOR empcursor IS SELECT * FROM EMP;

BEGIN

OPEN empcursor;FETCH empcursor BULK COLLECT INTO etab;FORALL i IN etab.first..etab.last

insert into employ values etab(i);

END;Note : can be used only if indexed numbers aresequential


Using RETURNING & FORALL

DECLARE

TYPE EmpTabType IS TABLE OF EMP.EMPNO%TYPE;emps EmpTabType;


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BEGINDELETE FROM EMP WHERE HIREDATE LIKE '%81'

RETURNING empno BULK COLLECT INTO emps;dbms_output.put_line('Deleted Records are');FORALL i IN emps.first..emps.last

INSERT INTO DELETED_EMPS VALUES(emps(i));END;


The INDICES OF clause replaces the lower_bound..upper_bound to indicate that all valid index valuesshould be processed, even if there are gaps. It looks like

this:


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FORALL index_name IN INDICES OF collection_name[BETWEEN lower_bound AND upper_bound]

sql_statement;

You can still limit the range processed by using the

BETWEEN syntax, which is optional.

Ex:FORALL i IN INDICES OF etab

insert into employ values etab(i);Note: can be used even if indexes are non-sequential(sparse)


CREATE TABLE ENAME_TABLE(names varchar2(12));

DECLARETYPE ename_table_type IS TABLE OF varchar2(12)d b l


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index by pls_integer;enames ename_table_type;

BEGINFOR rec IN (select empno,ename from emp) LOOP

enames(rec.empno):=rec.ename;

END LOOP;FORALL x IN INDICES OF enamesinsert into ename_table values(enames(x));

END;


The VALUES OF clause enables you to processthe main collection in a different sequence. Youcreate a second collection containing only theindex numbers you want to process, in the orderyou want them processed


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you want them processed.The statement then becomes:

FORALL index_name IN VALUES OFindex_collection

sql_statement;

Note:

-index cannot be used in iteration-dbms_output.put_line debug statement cannot be usedin iteration


CREATE TABLE ENAME_TABLE(names varchar2(12));

DECLARETYPE empno_tab_type IS TABLE OF emp.ename%type

INDEX BY l i t


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INDEX BY pls_integer;empnames empno_tab_type;

TYPE index_table_type IS TABLE OF pls_integer;idx_tab index_table_type;

BEGINFOR rec IN (select empno,ename from emp) LOOP

empnames(rec.empno):=rec.ename;END LOOP;select empno bulk collect into idx_tab from emp;

FORALL x IN VALUES OF idx_tabinsert into ename_table select ename from emp where

ename=empnames(x);END;


Nested Table Multiset Operations


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dbms_output.put_line('Distinct of t2 copied to t3');t3:=set(t2);for i IN t3.first..t3.last loop

dbms_output.put_line(t3(i));end loop;dbms output put line('t1 multiset union [distinct] t2');


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dbms_output.put_line( t1 multiset union [distinct] t2 );t3:=t1 multiset union distinct(t2);

for i IN t3.first..t3.last loopdbms_output.put_line(t3(i));

end loop;dbms_output.put_line('t1 multiset intersect t2');t3:=t1 multiset intersect(t2);for i IN t3.first..t3.last loop

dbms_output.put_line(t3(i));

end loop;END;


VARRAYS

DECLARE

TYPE NumList IS VARRAY(3) OF VARCHAR2(12);nums NumList := NumList(10,20,30);BEGIN


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for i in 1..3 loopDBMS_OUTPUT.PUT_LINE(nums(i));

end loop;nums(1):='A';nums(2):=60;nums(3):='welcome';

for i in 1..3 loopDBMS_OUTPUT.PUT_LINE(nums(i));end loop;

END;


Nested table column example

CREATE TYPE HOBBY_TAB_TYPE IS TABLE OF VARCHAR2(15);

CREATE TABLE EMPHOBBIES(empno NUMBER(4),ename VARCHAR2(12),


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ename VARCHAR2(12),hobbies HOBBY_TAB_TYPE)

NESTED TABLE hobbies STORE AS HOBBY_EXT_TAB;

INSERT INTO EMPHOBBIES VALUES(7369,'SMITH',HOBBY_TAB_TYPE('FOOTBALL','CRICKET','MOVIES','SWIMMING'))

INSERT INTO EMPHOBBIES VALUES(7566,'JONES',HOBBY_TAB_TYPE('TV','SNOOKER','READING'));

SELECT * FROM EMPHOBBIES;

SELECT * FROM TABLE(SELECT HOBBIES FROM EMPHOBBIES WHEREEMPNO=7369);


SELECT E.EMPNO,E.ENAME,H.*FROM EMPHOBBIES E,TABLE(E.HOBBIES) H;

INSERT INTO TABLE(SELECT HOBBIES FROM EMPHOBBIES

WHERE EMPNO=7566)VALUES('TENNIS');


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UPDATE TABLE(SELECT HOBBIES FROM EMPHOBBIES

WHERE EMPNO=7369)SET COLUMN_VALUE='READING' WHERECOLUMN_VALUE='SWIMMING';

DELETE TABLE(SELECT HOBBIES FROM EMPHOBBIES

WHERE EMPNO=7369)WHERE COLUMN_VALUE='CRICKET';


Using collections in database columns

CREATE TYPE ITEM_TYPE IS OBJECT(

ITEM_NAME VARCHAR2(12),ITEM_QTY NUMBER(2),ITEM_PRICE NUMBER(9,2));


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CREATE TYPE ITEM_TAB_TYPE IS TABLE OF ITEM_TYPE;

CREATE TABLE INVOICE(INVOICE_NUM NUMBER(4),CUST_NAME VARCHAR2(12),

ITEM_DETAILS ITEM_TAB_TYPE)NESTED TABLE ITEM_DETAILS STORE AS ITEM_EXT_TABLE;

DESC INVOICE

DESC ITEM_EXT_TABLE


INSERT INTO INVOICE VALUES(1001,'PRAKASH',ITEM_TAB_TYPE(

ITEM_TYPE('P4 CPU',2,4500),ITEM_TYPE('INTEL M B',2,4750),

ITEM_TYPE('512MB RAM',3,1500)));

INSERT INTO INVOICE VALUES(1002,'MOHAN',


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( , ,ITEM_TAB_TYPE(

ITEM_TYPE('KEYBOARD',5,450),ITEM_TYPE('SPEAKERS',3,370),ITEM_TYPE('ATX CABINET',3,1150),ITEM_TYPE('80GB HDD',2,5500)))

SELECT * FROM INVOICE;

SELECT ITEM_NAME,ITEM_QTY,ITEM_PRICE

FROM THE (SELECT ITEM_DETAILSFROM INVOICE WHERE INVOICE_NUM=1001);


SELECT * FROMTABLE(SELECT ITEM_DETAILSFROM INVOICEWHERE INVOICE_NUM=1001);

SELECT


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SELECTI.INVOICE_NUM,

I.CUST_NAME,LI.ITEM_NAME,LI.ITEM_QTY,LI.ITEM_PRICEFROM INVOICE I,TABLE(I.ITEM_DETAILS) LI;

Now you can create a view for the above statement


CREATE VIEW INVOICE_ITEMASSELECTI.INVOICE_NUM,

I.CUST_NAME,LI.ITEM_NAME,LI.ITEM_QTY,


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LI.ITEM_PRICE

FROM INVOICE I,TABLE(I.ITEM_DETAILS) LI;

Now we can query the view using item_name

SELECT * FROM INVOICE_ITEM

WHERE ITEM_NAME='80GB HDD';

To find total invoice amount for each customer

SELECT I.INVOICE_NUM,I.CUST_NAME,SUM(LI.ITEM_QTY*LI.ITEM_PRICE) "Total Amount"FROM INVOICE I,TABLE(I.ITEM_DETAILS) LIGROUP BY I.INVOICE_NUM,I.CUST_NAME


Performing DML operation on nested table column

Inserting into nested table column

INSERT INTO THE(SELECT ITEM_DETAILS FROM INVOICEWHERE INVOICE_NUM=1001)VALUES('120GB HDD',2,6500);


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Updating a nested table column

UPDATE TABLE(SELECT ITEM_DETAILS FROM INVOICEWHERE INVOICE_NUM=1002)SET ITEM_PRICE=5200,ITEM_QTY=4 WHERE ITEM_NAME='80GB

HDD';

Deleting a nested table row

DELETE FROM TABLE(SELECT ITEM_DETAILS FROMINVOICE WHERE INVOICE_NUM=1002)WHERE ITEM_NAME='KEYBOARD';


varray in database columns

CREATE TYPE HOBBIES_ARRAY AS VARRAY(3) OF VARCHAR2(15);

CREATE TABLE PERSON(name VARCHAR2(12) PRIMARY KEY,HOBBY HOBBIES ARRAY);


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HOBBY HOBBIES_ARRAY);

INSERT INTO PERSON VALUES('PRAKASH',HOBBIES_ARRAY('CRICKET','MOVIES','READING'))

INSERT INTO PERSON VALUES('GANESH',

HOBBIES_ARRAY('FOOTBALL','TENNIS','TV'));

SELECT * FROM PERSON;

SELECT * FROM TABLE(SELECT HOBBY

FROM PERSON WHERE NAME='PRAKASH');

SELECT P.NAME,H.*FROM PERSON P,TABLE(P.HOBBY) H;


While updating we have to update entine collection

UPDATE PERSON SET HOBBY=HOBBIES_ARRAY('FOOTBALL')WHERE NAME='PRAKASH';

When listed PRAKASH will be having only 'FOOTBALL' value

SELECT P NAME H *


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SELECT P.NAME,H.*

FROM PERSON P,TABLE(P.HOBBY) H;

SELECT P.NAME,H.*FROM PERSON P,TABLE(P.HOBBY) HWHERE COLUMN_VALUE='FOOTBALL';


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