unit-3 PL SQL-new

8/6/2019 unit-3 PL SQL-new

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INTRODUCTION TO PL/ SQL

By :Mrs. Suman Madan

[email protected]

Procedural Language Extension to SQL


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PL/SQL Allows using general programming tools with SQL, for example: loops,

conditions, functions, etc.

This allows a lot more freedom than general SQL, and is lighter-weightthan JDBC.

We write PL/SQL code in a regular file, for example PL.sql, and load it

with @PL in the sqlplus console.

Advantages :

Support for SQL

Higher productivity

Better performance Portability

Integration with oracle


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Architecture of PL SQL

ORACLE SERVER

PL SQL ENGINE

PL SQL BLOCK

SQL Statement Executor

S

Q

L

PROCEDURAL STATEMENT EXECUTOR


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PL SQL CHARACTER SET

Upper and lower case letters

Numerical form

All special symbols and characters

Tab ,space and carriage return

All arithmetic operators


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CONTROL STRUCTURES

CONDITIONAL CONTROL

ALL THE BASIC IF CONDITIONS

ITERATIVE CONTROLLOOP ,FOR LOOP ,WHILE LOOP

SEQUENTIAL CONTROLGOTO


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PL/SQL Blocks

PL/SQL code is built of Blocks, with a unique structure. There are two types of blocks in PL/SQL:

1. Anonymous Blocks: have no name (like scripts)

can be written and executed immediately in SQLPLUS

can be used in a trigger

2. Named Blocks:

Procedures

Functions


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INTRODUCTION TO PLSQL BLOCK

PLSQL BLOCK IS DIVIDED INTO THREE PARTS

DECLARATIVE

EXECUTABLE

EXCEPTION HANDLING

DECLARE

{ DECLARATIONS OF VARIABLES ETC. }

BEGIN

{ EXECUTABLE STATEMENTS }

EXCEPTION

{ HANDLERS }

END;


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SAMPLE PROGRAME1Declare

com emp.comm%type;

Begin

select comm into com from emp where empno=7876;

if com is null then

update emp set comm=100 where empno=7876;

else

update emp set comm=200 where empno=7876;end if;

End;

/


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Declaring Variables with the

%TYPE Attribute

Examples

DECLARE

sname Sailors.sname%TYPE;fav_boat VARCHAR2(30);my_fav_boat fav_boat%TYPE := 'Pinta';...

Accessing column snamein table Sailors

Accessinganother variable


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Declaring Variables with the

%ROWTYPE Attribute

Declare a variable with the type of a ROW of a table.

And how do we access the fields in reserves_record?

reserves_record.sid:=9;

Reserves_record.bid:=877;

reserves_record Reserves%ROWTYPE;

Accessingtable

Reserves


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Creating a PL/SQL RecordA record is a type of variable which we can define (like

struct in C or object in Java)DECLARE

TYPE sailor_record_type IS RECORD(sname VARCHAR2(10),

sid VARCHAR2(9),age NUMBER(3),

rating NUMBER(3));

sailor_record sailor_record_type;

...BEGIN

Sailor_record.sname:=peter;Sailor_record.age:=45;


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CURSOR MANAGEMENT

A work area called private sql area is used by the

Oracle server to execute SQL statements and

to store processed information.

PLSQL uses cursors to name the private area and

to access the stored information.


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Types of CURSORS

There are two types of cursors

EXPLICIT CURSOR

IMPLICIT CURSOR

Syntaxcursor is


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Creating a Cursor We create a Cursor when we want to go over a result of

a query

Syntax Example:

DECLAREcursor c is select * from sailors;

sailorData sailors%ROWTYPE;

BEGINopen c;

fetch c into sailorData;

sailorData is a

variable thatcan hold aROW from thesailors table

Here the firstrow of sailorsis inserted intosailorData


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Explicit cursor

The set of rows returned by the query can contain zero ormultiple rows depending upon the query defined.

These rows are called the active set.

The cursor will point to the current row in active set.

Once the cursor id defined ,we can use it using the followingcommands to control the cursor.

OPEN - it executes the query

identifies the active set

first row is pointed

Syntax open ;

FETCH - retrieves the current row and the next rows

Syntax fetch into ;

CLOSE - After processing the last row in the active set-cursoris disabled

Syntax Close


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Explicit Cursor Attributes

Obtain status information about a cursor.

Attribute Type Description

%ISOPEN Boolean Evaluates to TRUE if the cursoris open.

%NOTFOUND Boolean Evaluates to TRUE if the mostrecent fetch does not return a row.

%FOUND Boolean Evaluates to TRUE if the mostrecent fetch returns a row;complement of %NOTFOUND

%ROWCOUNT Number Evaluates to the total number ofrows returned so far.


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The following example illustrates explicit cursors.

Declare

msal emp.sal%type;Cursor c1 is select sal from emp where empno =7876;

begin

Open c1;

loop

fetch c1 into msal;

msal:=msal+msal*0.1;

update emp set sal=msal where empno=7876;

exit when c1 % notfound;

dbms_output.put_line('one row updated');end loop;

close c1;

end;

/


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Example 1- %notfoundDeclare

cursor c_emp is select emp_code,salary from employee where deptno=10;

Str_emp_code employee.emp_code%type;

Num_salary employee.salary%type;Begin

open c_emp;

loop

fetch c_emp into str_emp_code, num_salary;

exit when c_emp%notfound;

Update employee set salary=num_salary+(num_salary*0.5)

where emp_code=str_emp_code;

Insert into emp_raise values(str_emp_code,sysdate,num_salary*0.5);

End loop;

Commit;Close c_emp;

End;

/


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Example 2- %foundDeclare




open c_emp;

loop


if c_emp%found then

Update employee set salary=num_salary+(num_salary*0.5)where emp_code=str_emp_code;


else exit;

end if;

End loop;

Commit;

Close c_emp;

End;

/

E l 3 %i


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Example 3- %isopen

Declare




open c_emp;

If c_emp%isopen then

loop


Update employee set salary=num_salary+(num_salary*0.5)

where emp_code=str_emp_code;


End loop;

Commit;

Close c_emp;Else dbms_output.put_line(unable to open the cursor);

End if;

End;

/

E l % t


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Example - %rowcount

display the names,dname and salary of first 5 employees

Declare

Cursor c_emp is select ename,emp.deptno,sal from emp,dept where

dept.deptno=emp.deptno order by sal desc;n emp.ename%type;

d emp.deptno%type;

s emp.sal%type;

Begin

open c_emp;dbms_output.put_line(name department salary);

dbms_output.put_line(------- ------------- -------);

Loop

fetch c_emp into n,d,s;

dbms_output.put_line(n|| ||d|| ||s);

exit when c_emp%rowcount=5;

End loop;

End;

/


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Example - %isopen

Declare

Cursor c4 is select ename,sal from emp where empno=7876;

Begin

If c4%isopen then

Dbms_output.put_line('this message is not displaced');

Else

Open c4;Dbms_output.put_line('cursor opened');

End if;

Close c4;

End;

/

Example with accounts table(accno bal)


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Example with accounts table(accno,bal)

Display the first 3 accounts having highest balance

Declare

Cursor c2 is select accno,bal from account order by bal desc;a accounts.accno%type;

b accounts.bal%type;

Begin

Open c2;

Loop

fetch c2 into a,b;

dbms_output.put_line(a|| ||b);

exit when c2%rowcount=3;

End loop;

End;

/


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Example

DECLARE

Pi constant NUMBER(8,7) := 3.1415926;

area NUMBER(14,2);

cursor rad_cursor is select * from RAD_VALS;

rad_val rad_cursor%ROWTYPE;

BEGIN

open rad_cursor;

fetch rad_cursor into rad_val;

area:=pi*power(rad_val.radius,2);

insert into AREAS values (rad_val.radius, area);

close rad_cursor;

END;

/

radius

3

6

8

Rad_cursor

fetc

hRad_val

Radius AreaAREAS

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RAD_VALS

Rad_cursor

fetc

hRad_val

Radius Area

3 28.27

DECLARE DECLARE


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DECLAREcursor rad_cursor is select * from RAD_VALS;rad_val rad_cursor%ROWTYPE;

BEGINopen rad_cursor;fetch rad_cursor into rad_val;

area:=pi*power(rad_val.radius,2);insert into AREAS values (rad_val.radius,area);

DECLARE

cursor rad_cursor is select * fromRAD_VALS;

rad_val RAD_VALS%ROWTYPE;BEGINopen rad_cursor;fetch rad_cursor into rad_val;area:=pi*power(rad_val.radius,2);insert into AREAS values

(rad_val.radius, area);

DECLARE

cursor rad_cursor is select radius from

RAD_VALS;rad_val RAD_VALS.radius%TYPE;

BEGINopen rad_cursor;fetch rad_cursor into rad_val;area:=pi*power(rad_val,2);insert into AREAS values (rad_val, area);

DECLAREcursor rad_cursor is select * from

RAD_VALS;rad_val RAD_VALS.radius%TYPE;

BEGIN

open rad_cursor;fetch rad_cursor into rad_val;area:=pi*power(rad_val,2);insert into AREAS values (rad_val, area);

l


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Implicit cursor Implicit cursor attributes can be used to access information about the most

recently executed SQL statement. The most recently executed SQL statement isreffered as SQLCURSOR.

The implicit cursor attributes are :

1. %notfound

2. %found

3. %rowcount

4. %isopen

%NOTFOUND: The %notfound attribute evaluate to true if DML statements donot return any row, else it evaluate to false.

EXAMPLE :

Begin

Delete from customer where name=RAO;

If sql %notfound then

Dbms_output.put_line(value not found);

End if;End;


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%FOUND: The %found attribute is the logical opposite of the %notfound attribute.

The %found attribute is evaluates to true if the SQL DML statement affects one ormore rows,else it is evaluated to false.

%ROWCOUNT: The %rowcount attribute counts the number of rows returned by anSQL DML statement .the %rowcount will return zero if the DML statements does

not affect any row.

The following example uses the %rowcount attribute to check if the cursor fetchesany rows.

Declare

Cursor c1 is select name from customer where repid=10;

Cust_rec c1%rowtype;Begin

For cus_rec in c1

Loop

Update customer set name=vivek where repid =10;

If sql%rowcount >0 then Dbms_output.put_line(record exists);End if;

End loop;

End;


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SQL Impicit Cursor Attributes

SQL cursor is automatically created after each SQL

query. It has 4 useful attributes:

SQL%ROWCOUNT Number of rows affected by themost recent SQL statement (aninteger value).

SQL%FOUND Boolean attribute that evaluates toTRUE if the most recent SQLstatement affects one or more rows.

SQL%NOTFOUND Boolean attribute that evaluates toTRUE if the most recent SQL

statement does not affect any rows.

SQL%ISOPEN Always evaluates to FALSE becausePL/SQL closes implicit cursorsimmediately after they are executed.


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Solution (2)

BEGINupdate mylogset logon_num = logon_num + 1where who = user;

if SQL%ROWCOUNT = 0 theninsert into mylog values(user, 1);

end if;commit;END;

/

The salary of the employees is raised by 20% Write a pl/sql code to accept a empno


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The salary of the employees is raised by 20%. Write a pl/sql code to accept a empno

and update the sal and display some message

Begin

Update emp set sal=sal*.02 where empno=&empno;

Ifsql%notfound thenDbms_output.put_line(empno does not exist);

else

Dbms_output.put_line(record modified);

End if;

End;

Begin

Update emp set sal=sal*.02 where empno=&empno;

Ifsql%found thenDbms_output.put_line(record modified);

else

Dbms_output.put_line(empno does not exist);

End if;

End;

OR


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The salary of the employees is raised by 20% who are clerks. Write Pl/sql code to

accept empno & update sal and display some message.

Declare

Rows_effected char(4);Begin

Update emp set sal=sal*.02 where job=clerk;

Rows_effected:=to_char(sql%rowcount);

Ifsql%rowcount>0 thenDbms_output.put_line(rows_effected||rows updated);

else

Dbms_output.put_line(no employees as clerks);

End if;End;

%ISOPEN: %isopen is always evaluated to false.


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SELECT Statements

INTO clause is required.

Query must return exactly one row.

Otherwise, a NO_DATA_FOUND or TOO_MANY_ROWS exception

is thrown

DECLAREv_sname VARCHAR2(10);

v_rating NUMBER(3);BEGINSELECT sname, ratingINTO v_sname, v_rating

FROM SailorsWHERE sid = '112';END;/


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Conditional logic

If

then

elsif then

else

end if;

If

then

if

then

end if;

else

end if;

Condition: Nested conditions:


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IF-THEN-ELSIF Statements

. . .IF rating > 7 THENv_message := 'You are great';ELSIF rating >= 5 THENv_message := 'Not bad';ELSEv_message := 'Pretty bad';

END IF;. . .

Suppose we have the following table:


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Suppose we have the following table:

Want to keep track of how many

times someone logged on to the

DB

When running, if user is already in

table, increment logon_num.

Otherwise, insert user into table

logon_numwho

3Peter

4John

2Moshe

create table mylog(who varchar2(30),

logon_num number

);

mylog

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SolutionDECLAREcnt NUMBER;

BEGINselect count(*)into cntfrom mylogwhere who = user;

if cnt > 0 thenupdate mylogset logon_num = logon_num + 1

where who = user;

elseinsert into mylog values(user, 1);end if;commit;

end;

/

L Si l L


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Loops: Simple Loop

DECLARE

i number_table.num%TYPE := 1;BEGINLOOPINSERT INTO number_tableVALUES(i);

i := i + 1;EXIT WHEN i > 10;

END LOOP;END;

create table number_table(

num NUMBER(10)

);

L Si l C L


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Loops: Simple Cursor Loop

DECLAREcursor c is select * from number_table;

cVal c%ROWTYPE;BEGINopen c;LOOP

fetch c into cVal;EXIT WHEN c%NOTFOUND;insert into doubles values(cVal.num*2);

END LOOP;END;

create table number_table(

num NUMBER(10)

);

Loops: FOR Loop


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Loops: FOR Loop

DECLAREi number_table.num%TYPE;

BEGIN

FOR i IN 1..10 LOOPINSERT INTO number_table VALUES(i);

END LOOP;END;

Notice that i is incremented automatically

Loops: For Cursor Loops


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Loops: For Cursor Loops

DECLAREcursor c is select * from number_table;

BEGINfor num_row in c loop

insert into doubles_table

values(num_row.num*2);end loop;END;/

Notice that a lot is being done implicitly: declarationof num_row, open cursor, fetch cursor, the exitcondition

Loops: WHILE Loop


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Loops: WHILE Loop

DECLARETEN number:=10;i number_table.num%TYPE:=1;

BEGINWHILE i


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Printing Output

You need to use a function in the DBMS_OUTPUTpackage in order to print to the output

If you want to see the output on the screen, you must

type the following (before starting):set serveroutput on format wrapped size 1000000

Then print using

dbms_output. put_line(your_string); dbms_output.put(your_string);


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Input and output example

set serveroutput on format wrap size 1000000

ACCEPT high PROMPT 'Enter a number: '

DECLARE

i number_table.num%TYPE:=1;

BEGIN

dbms_output.put_line('Look Ma, I can print from PL/SQL!!!');WHILE i


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Anonymous Block Structure:DECLARE (optional)

/* Here you declare the variables you will use in this block */

BEGIN (mandatory)/* Here you define the executable statements (what the block

DOES!)*/

EXCEPTION (optional)

/* Here you define the actions that take place if an exception isthrown during the run of this block */

END; (mandatory)

/

Always put a new linewith only a / at the

end of a block! (This

tells Oracle to run the

block)

A correct completion of ablock will generate thefollowing message:

PL/SQL procedure

successfully completed


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Concept of error handling

There are 2 types of exceptions.

1.predefined exceptions

2.user-defined exceptions

predefined exception:- predefined exceptionsare raised automatically by the system duringrun time.

user-defined exceptions:- defined by the user


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Predefined exception:- predefined exceptions are raisedautomatically by the system during run time.

Syntax for predefined exception is as follows:

Begin

Sequence_of_statements;

ExceptionWhen then

Sequence_of_statements;

When others then /* the last exception in the

exception handler*/Sequence_of_statements;

End;

Trapping Exceptions


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Trapping Exceptions

Here we define the actions that should happen

when an exception is thrown. Example Exceptions:

NO_DATA_FOUND

TOO_MANY_ROWS

ZERO_DIVIDE

When handling an exception, consider

performing a rollback When multiple exception is raised, Only one

exception is raised and handled at any time

PREDFINED EXCEPTION


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PREDFINED EXCEPTIONNo_data_found : This is raised when select statement returns no

rows.

Cursor_already _open : This is raised when we try to open a cursorwhich is already opened.

Dup_val_on_index :This is raised when we insert duplicate values ina column, which is defined as unique index.

Storage_error : This is raised if PL/SQL runs out of memory.

Program_error : This is raised if PL/SQL has an internal problem.

Zero_error : when we divide a number with zero

Invalid _cursor : This is raised when we violate cursor operation.

Login_denied :This is raised when we try to enter oracle using invaliduser-name/password.

invalid _number :This is raised if the conversion of character string to

a number fails because the string does not represent

a valid number.

Too_many rows : returns more than one row.

Q A t l d di l th l d ti


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Q. Accept an employee no and display the sal and an exceptionhandler.

declare

mempno emp.empno%type;

memp emp.sal%type;

begin

select sal into memp from emp where empno=&mempno;

dbms_output.put_line( the salary of that empno is||mempexception

when no_data_found then

dbms_output.put_line('there is no employee withempno);

end;

/

DECLARE


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DECLARE

num_row number_table%ROWTYPE;BEGIN

select *into num_row

from number_table;dbms_output.put_line(1/num_row.num);

EXCEPTIONWHENNO_DATA_FOUND THEN

dbms_output.put_line('No data!');WHEN TOO_MANY_ROWS THEN

dbms_output.put_line('Too many!');WHEN OTHERS THEN

dbms_output.put_line(Error);end;

USER DEFINED EXCEPTION:


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USER-DEFINED EXCEPTION:-

A user defined exceptions should be declared

and raised explicitly by a raise statement.it canbe declared only in the declarative part of thePL/SQL block.

SYNTAX:

exception;

SYNTAX FOR RAISE STATEMENT:

Raise ;

User-Defined Exception


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User-Defined ExceptionDECLARE

e_number1 EXCEPTION;

cnt NUMBER;BEGINselect count(*)into cntfrom number_table;

IF cnt = 1 THEN RAISE e_number1;ELSE dbms_output.put_line(cnt);END IF;

EXCEPTIONWHEN e_number1 THEN

dbms_output.put_line('Count = 1');

end;

declaremempno emp empno%type;

Example User


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mempno emp.empno%type;msal emp.sal%type;mcom emp.comm%type;

myexec exception;

mynextexec exception;begin

select sal,comm into msal,mcom from emp whereempno=&mempno;

dbms_output.put_line( the salary of that empno is||msal);If msal2000 then raise mynextexec;end if;

exceptionWhen myexec then

dbms_output.put_line(sal is less than 1000);

When mynextexec thendbms_output.put_line(sal is more than 2000);

when no_data_found thendbms_output.put_line('there is no employee with empno);

end;

/

Defined Exception


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Functions and Procedures

Up until now, our code was in an anonymousblock

It was run immediately

It is useful to put code in a function or

procedure so it can be called several times

Once we create a procedure or function in a

Database, it will remain until deleted (like a

Creating Procedures


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CREATE [OR REPLACE] PROCEDURE

procedure_name[(parameter1 [mode1] datatype1,parameter2[mode2] datatype2,. . .)]

IS|ASPL/SQL Block;

Creating Procedures

Modes:

IN: procedure must be called with a value for the parameter. Value cannotbe changed

OUT: procedure must be called with a variable for the parameter. Changesto the parameter are seen by the user (i.e., call by reference)

IN OUT: value can be sent, and changes to the parameter are seen by theuser

Default Mode is: IN

Example- what does this do?


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create or replace procedurenum_logged(person IN mylog.who%TYPE,

num OUT mylog.logon_num%TYPE)ISBEGIN

select logon_num

into numfrom mylogwhere who = person;

END;/

Example what does this do?

logon_

numwho

3Pete

4John

2Joe

Table mylog

Calling the Procedure


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declarehowmany mylog.logon_num%TYPE;

beginnum_logged(John',howmany);dbms_output.put_line(howmany);

end;/

Calling the Procedure

Errors in a Proced re


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Errors in a Procedure

When creating the procedure, if there are errors in itsdefinition, they will not be shown

To see the errors of a procedure called myProcedure,

typeSHOW ERRORS PROCEDURE myProcedure

in the SQLPLUS prompt

For functions, typeSHOW ERRORS FUNCTION myFunction

Creating a Function


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Creating a Function

Almost exactly like creating a procedure, but

you supply a return type

CREATE [OR REPLACE] FUNCTIONfunction_name

[(parameter1 [mode1] datatype1,parameter2[mode2] datatype2,. . .)]

RETURN datatypeIS|ASPL/SQL Block;


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create or replace functionrating_message(rating IN NUMBER)return VARCHAR2

ASBEGIN

IF rating > 7 THENreturn 'You are great';

ELSIF rating >= 5 THENreturn 'Not bad';

ELSEreturn 'Pretty bad';END IF;

END;/

A Function

NOTE THAT YOU

DON'T SPECIFY THE

SIZE

C lli th f ti


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declarepaulRate:=9;

Begindbms_output.put_line(ratingMessage(paulRate));end;/

Calling the function

Creating a function:


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create or replace function squareFunc(num in number)

return number

isBEGIN

return num*num;

End;

/

BEGIN

dbms_output.put_line(squareFunc(3.5));

END;

/

Creating a function:

Using the function:

DATABASE TRIGGERS


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DATABASE TRIGGERS A database trigger is a stored procedure that is fired when an

insert, update or delete statement is issued against the

associated table.

Database triggers can be used for the following purposes.

To generate data automatically.

To enforce complex integrity constraints.

To customize complex security authorizations.

To maintain replicate tables.

To audit data modifications.

SYNTAX: Create or replace trigger


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SYNTAX: Create or replace trigger

[before/after]

[insert/update/delete] on

[for each statement/for each row]

[when ];

PARTS OF TRIGGER: THERE ARE 3 PARTS OF TRIGGER:

1.TRIGGER STATEMENTS: The trigger statement specifies the DML

statement like update,delete and insert and it fires the trigger body. It

also specifies the table to which the trigger is associated.

2.TRIGGER BODY: It is PL/SQL block that is executed when a

triggering statement is issued.

3.TRIGGER RESTRICTION: Restrictions on a trigger can be achieved

using the WHEN clause.WHEN clause is evaluated for each row that

is affected by the trigger.

EXAMPLE 1:


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EXAMPLE 1:Create or replace trigger trig

Before insert

On emp

For each row

Declare

eno emp.empno%type;Begin

Select empno into eno from emp where deptno=10;

If eno =1000 then

Raise_application_error(-20001,enter some other number);End if;

End;

EXAMPLE 2:


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Create or replace trigger sun_trig

Before insert or update or delete

On emp

Declare

enter_date char;

Begin

enter_date := to_char(sysdate ,dy);

If enter_date in(sat,sun) then

Raise_application_error(-20001,try on any

weekdays);End if;

End;

application error_numbers is20000 to -20999

Message is character string up to 2048 bytes of length

ENABLING AND DISABLING TRIGGERS:


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A triggers can be enabled or disabled. An enabled trigger executesthe trigger body if the triggering statements is issued. By default,triggers are enabled. Disabled trigger does not execute the trigger

body even if the triggering statements is issued.

SYNTAX:

Alter trigger disable;

DROPPING TRIGGER:

To drop a trigger from the database, the drop trigger command isused.

SYNTAX:

Drop trigger;

>Alter table emp

Disable all triggers;


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EXAMPLES

Example Programs - LOOP


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p g

declare

a number : = 100;

begin

loop

a := a + 25 ;exit when a=250;

dbms_output.put_line(a);

end loop;

end;

/

Example Programs - WHILE


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p g

declare

i number:=0;

j number := 0;

begin

while i


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p g

declare

a emp.empno%type;b emp.sal%type;

begin

for i in 1..5

loopupdate emp set sal=1000 where empno=7876;

select empno,sal into a,b from emp where empno=7876;

dbms_output.put_line(a);

dbms_output.put_line(b);

end loop;

end;

/

Example Programs - FOR


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p g

declare

amt number(10,2);i number;

begin

amt:=2000;

for i in 1..5 loop

amt:=amt+100;

dbms_output.put_line(amt);

end loop;end;

/

EXAMPLE - FOR %FOUND&%ROWCOUNT


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declare

Cursor c2 is select empno,ename,sal,comm from emp where deptno=10;

s emp.sal%type;

c emp.comm%type;e emp.empno%type;

n emp.ename%type;

Begin

Open c2;

LoopFetch c2 into e,n,s,c;

If c2%found then

Dbms_output.put_line('fetches more than two rows');

Dbms_output.put_line(e||n||s||c);

else

Exit when c2%rowcount>2;

End if;

End loop;

Close c2;

End;

/

EXAMPLE : pl/sql code for cursor for loop


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Declare

Cursor for_cus is select name from customer where city=hyd;

a for_cus%rowtype;

Begin

For cust_rec in fro_cur loop

Delete from customer where name=readymoney;

Commit;

End loop;

Dbms_output.put_line(name has been deleted);

End;

Example :Check for the employee called rao and delete the record


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Declare

Cursor for_emp is select ename from emp ;

a for_emp%rowtype;

Begin

For cust_rec in for_emp

loop

exit when for_emp%notfound;

Delete from emp where ename='rao' ;Commit;

End loop;

Dbms_output.put_line('name has been deleted');

End;/

DECLARE

CURSOR c1 is


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CURSOR c1 is

SELECT ename, empno, sal FROM emp

ORDER BY sal DESC; -- start with highest-paid employee

my_ename CHAR(10);

my_empno NUMBER(4);my_sal NUMBER(7,2);

BEGIN

OPEN c1;

FOR i IN 1..5 LOOPFETCH c1 INTO my_ename, my_empno, my_sal;

EXIT WHEN c1%NOTFOUND;

/* in case the number requested is more than the total number of employees*/

INSERT INTO temp VALUES (my_sal, my_empno, my_ename);

COMMIT;END LOOP;

CLOSE c1;

END;

/

DECLARE


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acct_balance NUMBER(11,2);

acct CONSTANT NUMBER(4) := 3;

debit_amt CONSTANT NUMBER(5,2) := 500.00;

BEGIN

SELECT bal INTO acct_balance FROM accounts

WHERE account_id = acct FOR UPDATE OF bal;

IF acct_balance >= debit_amt THEN

UPDATE accounts SET bal = bal - debit_amt WHERE account_id = acct;

ELSE

INSERT INTO temp VALUES (acct, acct_balance, 'Insufficient funds');

-- insert account, current balance, and message

END IF;COMMIT;

END;

/

DECLAREsalary emp.sal%TYPE;


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mgr_num emp.mgr%TYPE;

last_name emp.ename%TYPE;

starting_empno CONSTANT NUMBER(4) := 7902;

BEGIN

SELECT sal, mgr INTO salary, mgr_num FROM emp

WHERE empno = starting_empno;

WHILE salary < 4000 LOOP

SELECT sal, mgr, ename INTO salary, mgr_num, last_name

FROM emp

WHERE empno = mgr_num;

END LOOP;

INSERT INTO temp VALUES (NULL, salary, last_name);COMMIT;

END;

/

use of %ROWTYPE is allowed. (Column names in a cursor declaration


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** must have aliases if they are not simple names.)

DECLARE

CURSOR my_cursor IS SELECT sal + NVL(comm, 0) wages, ename FROM emp;

my_rec my_cursor%ROWTYPE;

BEGIN

OPEN my_cursor;

LOOP

FETCH my_cursor INTO my_rec;

EXIT WHEN my_cursor%NOTFOUND;

IF my_rec.wages > 2000 THEN

INSERT INTO temp VALUES (NULL, my_rec.wages, my_rec.ename);

END IF;

END LOOP;

CLOSE my_cursor;

END;

This block calculates the total wages (salary plus commission) paid to employees in department20. It also determines how many of the employees have salaries higher than $2000, and how

h i i l th th i l i


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many have commissions larger than their salaries.

DECLARE

CURSOR emp_cursor(dnum NUMBER) IS

SELECT sal, comm FROM emp WHERE deptno = dnum;

total_wages NUMBER(11,2) := 0;

high_paid NUMBER(4) := 0;

higher_comm NUMBER(4) := 0;

BEGIN

/* The number of iterations will equal the number of rows returned by emp_cursor */

FOR emp_record IN emp_cursor(20)

LOOPemp_record.comm := NVL(emp_record.comm, 0);

total_wages := total_wages + emp_record.sal + emp_record.comm;

IF emp_record.sal > 2000.00 THEN


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high_paid := high_paid + 1;

END IF;

IF emp_record.comm > emp_record.sal THEN

higher_comm := higher_comm + 1;

END IF;

END LOOP;

INSERT INTO temp VALUES (high_paid, higher_comm,

'Total Wages: ' || TO_CHAR(total_wages));

COMMIT;

END;

/

Write a pl/sql code to accept account number and print the name and balance ofaccount holder.


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Tablename:bank

ACCNO NAME BAL

101 Renuka 5000102 madhu 2000

Declare

a number(3);

b number(7,2);

m varchar(10);

BeginSelect name,bal into m,b from bank where accno=&a;

Dbms_output.put_line(m||b);

End;

PROGRAM2: Write a pl/sql code accept accno, ttype and amount asinputs from the user to update balance and to print everything.


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p p p y g

TABLENAME:BANK

ACCNO NAME BAL

101 renu 6000102 satya 6000

103 madhu 7000

Declare

a bank.accno%type;

n bank.name%type;

b bank.bal%type;

ttype varchar(1);

amt number(7,2);begin

a:=&a ;

select name,bal into n,b from bank where accno=a;

ttype:=&ttype;

t t


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amt:=amt;

if ttype=c then

update bank set bal=b+amt where accno=a;

elsif

ttype=d then

update bank set bal=b-amt where accno=a;

else

dbms_output.put_line(invalid transaction);

end if;

dbms_output.put_line(a|| ||n||||b);

end;

PROGRAM NO 3Write a pl/sql code to take a customer number as input

d d hi d i h 5% i


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and update his due amount with 5% interest

TABLE NAME:CUSTOMER

CODE NAME DAMT

1 Anu 5000

2 Aryani 1000

3 Madhu 900

Declare

c customer.code%type;

n customer.name%type;d customer.damt%type;

Begin

C:=&c;Select name,damt into m,d from customer where code=c;

Update customer set damt=damt+dmt*0.05 where code=c;

Dbms_output.put_line(c|| ||m|| ||d);

End;

PROGRAM NO:4Write a PL/SQL code to accept code as input from the user,check for the due amt.if the

d i d l h d f h bl


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due amount is zero delete the record from the table.

TABLENAME:CUST

CODE NAME DAMT

101 A 700

102 B 700103 C 800

Declare

a cust.code%type;

b cust.damt%type;

Begina:=&a;

select damt into b from cust where code=a ;

if b=0 then

delete from cust where code=a;else

dbms_output.put_line(damt is not zero);

end if;

end;

PROGRAM NO.5Write a PL/SQL code to accept a customer code as input check for the due amount,if thedue amount is zero delete the record from the table use procedure for the above


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due amount is zero,delete the record from the table.use procedure for the aboveprogrram.

TABLE NAME:CUSTOMER

CODE NAME DAMT101 divya 580102 eistein 790103 fathima 0

Declarec customer.code%type;

m customer.name%type;d customer.damt%type;

Beginc:=&c;

Select damt ,name into d,m from customer where code=c;If d=0 then Goto dele;ElseDbms_output.put_line(damt is not zero);Endif;

delete from customer where code=c;

end;

PROGRAM NO.6 Write a PL/SQL code to accept a student no. and give them a graceof 10 marks,if his total is in between 250 and 255.


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TABLE NAME:STUDENT

SNO NAME TOT

101 Anu 250

102 ARYU 245

103 CLINTON 255

Declare

r student.sno%type;

m student.name%type;

t student.tot%type;begin

r:=&r;

select name,tot into m,t from student where rno=r;

if t>=250 and t


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every student who secured total marks between 250 & 255TABLENAME: student

RNO NAME TOTAL

101 a 260

102 b 245103 c 279

Declare

r stud.r no%type;

n stud.name%typet stud.total%type;

begin

update student set total=total+10 where

total>=250 and total>=255;end;

PROGRAM 8 Write a pl/sql code to read a record from a


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OG 8 W te a p /sq code to ead a eco d o a

table and store the rows in the second tableTABLENAME: student

RNO NAME TOTAL

101 a 260

102 b 245

103 c 279

TABLENAME:TEMP

RNO NAME TOTAL

Declarer student.rno %type;

n student.name%type;

t student.total%type;

beginr:=&r;

select name, total into n,t from student where rno=r;

insert into temp values(r,n,t);

end;

PROGRAM NO9 : Create a student table with rno and name.Create a marks table with rno marks and total


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Create a marks table with rno,marks and total.Write a pl/sql code to accept rno and display name,marks and total.TABLENAME:student

RNO NAMETABLENAME:MARKSRNO M1 M2 M3 TOTAL101 40 50 35 125

Declarer student.rno%type;

n student.name%type;a marks.m1%type;b marks.m2%type;c marks.m3%type;t marks.total%type;

beginr:=&r;select name,m1,m2,m3,total into n,a,b,c,t from student,marks

where student.rno=r and marks.rno=r;dbms_output_put_line(n||||a||||b||||c||||t);

end;

PROGRAM10Write pl/sql code to calculate interest on due amount for a


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Write pl/sql code to calculate interest on due amount for a

particular candidate and add the amount to dueamount for

that customer interest is calculated.

Damt interest

>=10000 5%

>=5000 2.5%

>=2500 1.25%else 0.25%

TABLENAME CUSTOMER

CODE NAME DAMT

101 a 1000102 b 4000

103 c 6000

104 d 7000

Declare


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c customer.code%type; d customer.damt%type;

begin

c:=&c;select damt into d from customer where code=c;

if d>=10000 then

update customer set damt=d+a*5/100 where code=c;

elsif d>=5000 then

update customer set damt=d+a*2.5/100 where code=c;

elsif d>=2500 then

update customer set damt=d+a*1.25/100 where code=c;else

update customer set damt=d+a*0.25/100 where code=c;]

end if;

end;

PROGRAM 11Write a pl/sql code using pre defined exception


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Write a pl/sql code using pre-defined exception

to accept accno as input from the user and

display bal on the screen. Raise two exceptionwhen data not found and too many rows.

TABLENAME BANKACCNO NAME BAL

101 A 600

102 B 700

103 C 800

104 D 600

Declare

a bank accno%type;


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a bank.accno%type;

b bank.bal%type;

n bank.name%type;begin

a:=&a;

select name, bal into n,b from bank where accno=a;

dbms_output.put_line(n||||b);Exception

When no_data_found then

Dbms_output.put_line(record not found);

When too_many_rows thenDbms_output.put_line(too many rows);

End;

PROGRAM 12


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Write a pl/sql code using user defined exceptionto accept accno as input from the user andprint the bal on the screenRaise an exception if bal is zero or bal is null;

TABLE NAME BANK

ACCNO NAME BAL

101 A 0

102 B 2000103 C 4000104 D

Declarea bank.accno%type;


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a bank.accno%type;b bank.bal%type;n bank.name%type;

begina:=&a;

select name,bal into b,n from bank where accno=a;if b==0 or b is null then

raise e;else

dbms_output.put_line(n||||b);end if;

exceptionwhen e then

dbms_output.put_line(no bal exist);end;

PROGRAM 13Write a pl/sql code to accept accno and amt as input


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W te a p /sq code to accept acc o a d a t as put

from the user. If ttype=c update bal with amount. If

ttype=d update bal=bal-amt. Raise an exception ifttype as null;

TABLE NAME BANK

ACCNO NAME BAL TTYPE

101 A 4000 D

102 B 5000 C103 C 5000 NULL

Declaret bank.ttype%type; a bank.accno%type;


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b bank.bal%type; n bank.name%type;

amt number(7,2); e exception;

begina:=&a;

amt:=&amt;

select name,bal,ttype into n,b,t from bank where accno=a;

if t=c then update bank set bal=bal+amt whereaccno=a;

elsif t=d then update bank set bal=bal-amt where

accno=a;

elsif t=null then raise e;end if;

exception

when e then dbms_output.put_line(ttype is null);

end;

PROGRAM 14


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Write a pl/sql code to explain the use ofpredefined exception

TABLENAME BANK

ACCNO NAME BAL

201 A 5000202 B 6000

203 C 7000

Declare

m bank accno%t pe;


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m bank.accno%type;

b bank.bal%type;

begin

m:=&m;

select bal into b from bank where accno=m;


exception


dbms_output.put_line(not found);

end; PROGRAM 15

Write a pl/sql code to explain the use of predefined exceptions


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TABLENAME BANK

ACCNO NAME BAL

101 A 5000102 B 6000

103 D 5000

104 E 1000

PROGRAM

m bank.accno%type;

b bank.bal%type;begin

m:=&m;

select bal into b from bank where accno=m;


exception


dbms_output.put_line(not found);

end;

OUTPUT

SQL>sta p5

Enter value for m:204

Not found

PROGRAM 16Write a pl/sql code to fire a trigger before deletion. The user should not be allowed to

delete the record if bal=1000


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delete the record if bal=1000

TABLE NAME BANK

ACCNO NAME BAL

100 A 2000101 B 5000

102 V 1000

PROGRAM

Create or replace trigger trig4 before delete on bankDeclare

b bank.bl%type;

begin

select bal into b from bank where accno=101;

if b=1000 then raise_application_error(-2000,DELETION NOT POSIBLE);

end if;

end;

OUTPUT

SQL>sta renu

Tri er created

PROGRAM 17

Write a pl/sql code to fire a trigger before insertion. The user


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W te a p /sq code to e a t gge be o e se t o . e use

should not be allowed to insert any record on Wednesday.

PROGRAMCreate or replace trigger trig1 before insert on bank

Declare

S varchar(3);Begin

S:=to_char(sysdate,dd);

If s=wed then

Raise_application_error(-20020,insertion is not possible on wed);End if;

End;

PROGRAM 18 Write a pl/sql code to update balance with 30% interest using cursors.TABLENAME BANK

ACCNO NAME BAL


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100 A 2000

101 B 4000

102 CV 6000

Declare

b bank.bal%type;

n bank.name%type;

a bank.accno%type;

cursor c1 is select bal from bank where accno=101;

begin

open c1;

loop

fetch c1 into b;

exit when c1% notfound;

if c1% found then

update bank set bal=b*30/100 +b where accno=101;dbms_output.put_line(record update);

end if;

end loop;

close c1;

end;

PROGRAM 19Write a pl/sql code to display record using cursors and display appropriate message for records found and not

found


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TABLENAME BANK

ACCNO NAME BAL

100 A 2000

101 B 4000102 CV 6000

Declare

b bank.bal%type;

n bank.name%type;

a bank.accno%type;

cursor c1 is select bal from bank where accno=101;begin

open c1;

loop;

fetch c1 into b;

exit when c1%notfound;if c1%found then

dbms_output.put_line(record found);

end if;

end loop;

close c1;

PROGRAM 20 Write a pl/sql code with cursors to updatedamt with 5% interest and display message if not found


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TABLENAME CUSTOMER

CODE NAME DAMT100 A 500101 B 600102 C 700103 D 500

Declared customer.damt%type;c customer.code%type;

n customer.name%type;cusor c3 is select damt,name from customer where code=100;

beginopen c3;

loopfetch c3 into d,n;

exit when c3% not found;update customer set damt = damt * 5/100 + damt where

code100;dbms_output.put_line(d||||n);end loop;

close c3;

end;

PROGRAM 21Write a pl/sql code with implicit cursors to accept the accno and amount from the user and update the table.Display appropriate messages for found and not found. Display the updated bal on the screen.

TABLENAME BANK


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TABLENAME BANK

ACCNO NAME BAL

100 A 2000

101 B 4000

102 CV 6000

Declare

a number(5);

b number(7,2);

amt number(7,2);

beginamt:=&amt;

a:=&a;

update bank set bal=bal+amt where accno=a;

if sql%notfound then

dbms_ouput.put_line(not found);

else

select bal into b from bank where accno=a;

dbms_output.put_line(record found||b);

end if;

end;

1. Display employee names, department number and department names for all

Practice Sheet - JOINS


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p y p y p p

departments including the department in which no employee is currently

working.

2. Display all rows in the EMP table, which is the left table even if there is nomatch in the DEPT table. (left outer join)

3. Display all rows in the DEPT table, which is the right table even if there is no

match in the EMP table. (right outer join)

4. Display all rows in the EMP table, even if there is no match in the DEPT table.

It also retrieves all rows in the DEPT table, even if there is no match in the

EMP table.

5. Display the employee last name and employee number along with their

managers last name and manager number. (self join)

6. Display all employees including King, who has no manager. Order the results

by the employee number.

7. Create a query that displays employee last names, department numbers, and allthe employees who work in the same department as a given employee. Give

each column an appropriate label.

1. Create a PL/SQL block that selects the maximum department no fro DEPT

Practice Sheet PL/SQL/Cursor/Triggers/Procedure


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p

table and store it in a variable. Print the output on the screen.

2. Create a PL/SQL block that computes the commission amount for a given

employee based on the employee salary. Accept the employee number as userinput. If sal =1000 and sal 1500 then comm = 20% of sal. Update the

emp table with new commission amount for the employee.

3. Write a pl/sql code to display record of employees 1000 and 1001 using

cursors and display appropriate message for record found and not found.

4. Write a pl/sql code to fire a trigger before insertion of a record in EMP table.

The user should not be allowed to insert any record on Wednesday.

5. Write a pl/sql code to fire a trigger before deletion of a record from EMP table.

The user should not be allowed to delete the record if salary=1000

6. Write a PL/SQL procedure that accepts the salary of employee from the user

and add Rs. 2000 /- to the salary of all employees having salary less than theentered salary.

Date post:	07-Apr-2018
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