DAC training-batch -2020(PLSQL)

LOGO
PL/SQL
Introduction to PL/SQL
Data types in PL/SQL
Control Structures in PL/SQL
Functions in PL/SQL

LOGO
PL/SQL
Procedure
Cursor
Trigger
Exception In PL/SQL

PL/SQL
 PL/SQL is a combination of SQL along with the
procedural features of programming languages.
 Properties of programming as well as the great
interaction with database.
Points to Ponder:-
PLSQL IS NOT A CASE SENSITIVE LANGUAGE.
LOGO
Sub titleIntroduction to PL/SQL

PL/SQL
Points to be Ponder:-
LOGO
Sub titleComments in PL/SQL

PL/SQL
 DECLARE :- if you want to declare a variable in
plsql program then it takes place in declare
section.
 BEGIN:- is used to start the working of program.
 END:- is used to terminate the begin.
Points to Ponder:-
DELIMITER IS USED TO RUN (/)
LOGO
Sub titleImportant PL/SQL Concepts

PL/SQL
 SET SERVEROUTPUT ON :- is run after every time
when you login in a session.
LOGO
Sub titleWhat to do Previously

PL/SQL
DBMS_OUTPUT.PUT_LINE command
for e.g. if sal=10 and you want to print it.
Then it looks like
dbms_output.put_line(‘the salary is ‘ ||sal);
LOGO
Sub titleTo show OUTPUT on Your Screen

PL/SQL
Declare
Num number(11);
Begin
Num:=5;
End;
/
LOGO
Sub titleValue assign in Variable

PL/SQL
DECLARE
N NUMBER(11);
BEGIN
DBMS_OUTPUT.PUT_LINE('ENTER A NUMBER:-');
N:=&N;
DBMS_OUTPUT.PUT_LINE('THE VALUE IS'||N);
END;
/
LOGO
Sub titleUser’s Input for a Variable

PL/SQL
BEGIN
DBMS_OUTPUT.PUT_LINE(‘Hello World');
END;
/
LOGO
Sub titleSample program to print your ‘Hello World’

PL/SQL
Syntax:-
IF condition THEN
statement 1;
ELSE
statement 2;
END IF;
Points to Ponder:-
IF STATEMENT WORKS AS SIMILAR AS C OR C++
LOGO
Sub titleControl Structures in PL/SQL
IF STATEMENT

PL/SQL
DECLARE
Age number(11);
Begin
Age:=&age;
If age>18 then
Dbms_output.put_line(‘You can vote’);
Else
Dbms_output.put_line(‘You cannot vote’);
End if;
End;
/
LOGO
IF STATEMENT EXAMPLE

PL/SQL
Declare
A number(11);
Begin
Select sal into a from empcp where
ename='MARTIN';
If a>1000 then
Update empcp set comm=comm+1000 where
ename='MARTIN';
Else
Update empcp set comm=comm+500 where
ename='MARTIN';End if;End;/
LOGO
IF WITH SQL TABLE

PL/SQL
1)SIMPLE LOOP
2)WHILE LOOP
3)FOR LOOP
LOGO
LOOPS IN PL/SQL

PL/SQL
Print number from 1 to 10 using FOR loop
BEGIN
FOR i in [REVERSE] 1 ..10 Loop
Dbms_output.put_line(i);
END Loop;
End;
/
Points to Ponder:-
(For FOR LOOP has NO need to initialize variable i
explicitly but it need in while )
LOGO
FOR LOOP

PL/SQL
Print number from 1 to 10 using WHILE loop
Declare
i number(3):=0;
Begin
While i<10 loop
i:=i+1;
Dbms_output.put_line(i);
End loop;
End;
/
LOGO
WHILE LOOP

PL/SQL
LOOP
Statement 1;
Statement 2;
Exit condition
End loop;
LOGO
SYNTAX OF SIMPLE LOOP

PL/SQL
Declare
I number(2):=0;
Begin
Loop
dbms_output.put_line('Before Increment value of
variable I: ' || I);
I:=I+1;
dbms_output.put_line('After Increment value of
variable I: ' || I);
EXIT when (I>0);END loop;END;/
LOGO
SIMPLE LOOP EXAMPLE

PL/SQL
CASE (expression)
WHEN <value1> THEN action_blockl;
WHEN <value2> THEN action_block2;
WHEN <value3> THEN action_block3;
ELSE action_block_default;
END CASE;
LOGO
SYNTAX OF “CASE”

PL/SQL
Declare
a NUMBER :=55;
b NUMBER :=5;
arth_operation VARCHAR2(20) :='MULTIPLY';
BEGIN
dbms_output.put_line('Program started.' );
CASE (arth_operation)
WHEN 'ADD' THEN dbms_output.put_line('Addition of the numbers are:' || a+b );
WHEN 'SUBTRACT' THEN dbms_output.put_line('Subtraction of the numbers are: '||a-b );
WHEN 'MULTIPLY' THEN dbms_output.put_line('Multiplication of the numbers are: '|| a*b
);
WHEN 'DIVIDE' THEN dbms_output.put_line('Division of the numbers are:'|| a/b);
ELSE dbms_output.put_line('No operation action defined. Invalid operation');
END CASE;
dbms_output.put_line('Program completed.' );
END;
/
LOGO
EXAMPLE OF “CASE”

PL/SQL
 This is similar to passing parameters in
programming languages.
 We can pass values to the stored procedure and
function through these parameters or variables.
 This type of parameter is a read only parameter.
Points to Ponder:-
We can assign the value of IN type parameter to
a variable or use it in a query, but we cannot
change its value inside the procedure.
LOGO
Sub titleFunctions in PL/SQL
“IN” PARAMETER

PL/SQL
CREATE [OR REPLACE] FUNCTION function_name
(param_name1 IN data_type, param_name2 IN
data_type.. )
Here:-
(i)param_name1, param_name2... are unique parameter
names.
(ii) data_type - defines the DataType of the variable.
(iii) IN - is optional, by default it is a IN type parameter.
LOGO
“IN” PARAMETER SYNTAX

PL/SQL
 The OUT parameters are used to send the OUTPUT
from a procedure or a function.
 This is a write-only parameter i.e. we cannot pass
values to OUT parameter while executing the
stored procedure, but we can assign values to
OUT parameter inside the stored procedure and
the calling program can receive this output value.
LOGO
“OUT” PARAMETER

PL/SQL
CREATE [OR REPLACE] PROCEDURE
procedure_name
(param_name1 IN data_type, param_name2 IN
data_type , param_name3 OUT data_type)
Here:-
(i) param_name1, param_name2 are unique parameter
Names and can not be modified with in procedure.
(ii) param_name3 can be modified with in procedure.
(iii) data_type - defines the DataType of the variable.
LOGO
“OUT” PARAMETER SYNTAX

PL/SQL
CREATE OR REPLACE PROCEDURE procname_outparam (inparam1 in VARCHAR2,outParam2
OUT VARCHAR2)
IS
BEGIN
outParam2 := 'Hello World OUT parameter I am changeable parameter' || inparam1;
END;
/
Run it:-
DECLARE
outParam2 VARCHAR2(100);
inparam1 VARCHAR2(100);
BEGIN
Procname_outparam ('i am IN parameter',outParam2);
DBMS_OUTPUT.PUT_LINE(outParam2);
END;
/
LOGO
EXAMPLE ON “IN” AND “OUT”

PL/SQL
 The IN OUT parameter allows us to pass values
into a procedure and get output values from the
procedure.
 This parameter is used if the value of the IN
parameter can be changed in the calling program.
 By using IN OUT parameter we can pass values
into a parameter and return a value to the calling
program using the same parameter. But this is
possible only if the value passed to the procedure
and output value have a same data type.
LOGO
“INOUT” PARAMETER

PL/SQL
CREATE [OR REPLACE] PROCEDURE
procedure_name
(param_name IN OUT data_type)
Here:-
(i) param_name are unique parameter
Names and can not be modified with in procedure.
(ii) param_name3 can be modified with in procedure.
(iii) data_type - defines the DataType of the variable.
LOGO
“IN OUT” PARAMETER SYNTAX

PL/SQL
Functions is a standalone PL/SQL subprogram.
Like PL/SQL procedure, functions have a unique
name by which it can be referred. These are
stored as PL/SQL database objects. Below are
some of the characteristics of functions.
 Functions are a standalone block that is mainly
used for calculation purpose.
 Function use RETURN keyword to return the
value, and the data type of this is defined at the
time of creation.
LOGO
DEFINITION OF FUNCTION

PL/SQL
 A Function should either return a value or raise
the exception, i.e. return is mandatory in
functions.
Points to Ponder:-
* Function with no DML statements can be directly
called in SELECT query whereas the function with
DML operation can only be called from other
PL/SQL blocks.
* Function can also return the value through OUT
parameters other than using RETURN.
LOGO
What is Function

PL/SQL
CREATE OR REPLACE FUNCTION
<function_name>
(
< variable_name parameter IN/OUT <datatype>
)
RETURN <datatype>
[ IS | AS ]
<declaration_part>
BEGIN
<execution part>
RETURN (value/var);
END<function_name>; LOGO
SYNTAX OF FUNCTION

PL/SQL
create or replace function f_mul( x in int,y in int)
return int
as
z int;
begin
z:= x*y;
return(z);
End f_mul;
/
Points to Ponder:-
* calling function from select query
select f_mul(12,10) from dual;
* calling a function from a program
Declare
a int;b int;c int;
Begin
a:= &a;b:=&b;
c:=f_mul(a,b);
dbms_output.put_line('Result:' || c);End;/
LOGO
EXAMPLE ON FUNCTION

PL/SQL
Points to Ponder:-
* calling a function from procedure
(I) create or replace procedure proc_mul(x int,y int,z out int)
as
begin
z:=f_mul(x,y);
End;
/
(II) Declare
a int;
b int;
c int;
Begin
a:=&a;
b:=&b;
proc_mul(a,b,c);
dbms_output.put_line('value of a:' ||a || 'value of b:' ||b);
dbms_output.put_line(‘Multiplication of aXb is :-' || c);
End;
/
LOGO
EXAMPLE ON FUNCTION

PL/SQL
A Procedure is a subprogram unit that consists of
a group of PL/SQL statements. Each procedure in
Oracle has its own unique name by which it can
be referred. This subprogram unit is stored as a
database object. Below are the characteristics of
this subprogram unit.
 Procedures are standalone blocks of a program
that can be stored in the database.
 Call to these procedures can be made by referring
to their name, to execute the PL/SQL statements.
LOGO
Sub titleProcedure in PL/SQL
DEFINITION OF PROCEDURE

PL/SQL
 It is mainly used to execute a process in PL/SQL.
 It can have nested blocks, or it can be defined
and nested inside the other blocks or packages.
 The values can be passed into the procedure or
fetched from the procedure through parameters.
 Procedure can have a RETURN statement to
return the control to the calling block, but it
cannot return any values through the RETURN
statement.
 Procedures cannot be called directly from SELECT
statements. They can be called from another
block or through EXEC keyword. LOGO
DEFINITION OF PROCEDURE

PL/SQL
CREATE [OR REPLACE ] PROCEDURE <name>[(argvarDatatype,
argvarDatatype)]
IS/AS
<declaration>
BEGIN
Statement1
Statement2
-----------
-----------
EXCEPTION
Statement1
Statement2
----------
----------
END;/Note:-[] i.e OPTIONAL
LOGO
SYNTAX OF PROCEDURE

PL/SQL
CREATE OR REPLACE PROCEDURE proc_empcntno(vdesg emp.job%type)
AS
empcntno int;
BEGIN
select count(*) into empcntno from emp
where job=vdesg;
dbms_output.put_line('Entered Designation is:'||vdesg);
dbms_output.put_line('NO. of Employees:'||empcntno);
END ;
/
LOGO
EXAMPLE ON PROCEDURE

PL/SQL
* Executing Multiple Queries .
* Reduces no. of hits to DB.
* Improve DB performance and N/W
performance.
* Enhancebility.
* Reusability.
* Modularity.
LOGO
IMPORTANT POINT ABOUT PROCEDURE

PL/SQL
1) Exception
2)Exception Handling
3) Structure of Exception Handling.
4) Types of Exception Handling.
LOGO
Sub titleException in PL/SQL

PL/SQL
An error occurs during the program
execution is called Exception in PL/SQL.
PL/SQL facilitates programmers to catch
such conditions using exception block in
the program and an appropriate action is
taken against the error condition.
LOGO
WHAT IS EXCEPTION

PL/SQL
PL/SQL provides a feature to handle the
Exceptions which occur in a PL/SQL Block known
as exception Handling. Using Exception Handling
we can test the code and avoid it from exiting
abruptly.
When an exception occurs a messages which
explains its cause is received.
PL/SQL Exception message consists of three parts.
1) Type of Exception(Exception Handler)
2) An Error Code
3) A message
LOGO
EXCEPTION HANDLING

PL/SQL
DECLARE
Declaration section
BEGIN
Exception section
EXCEPTION
WHEN ex_name1 THEN
-Error handling statements
WHEN ex_name2 THEN
WHEN Others THEN
END LOGO
STRUCTURE OF HANDLING EXCEPTION

PL/SQL
There are 3 types of Exceptions.
a) Named System Exceptions
b) Unnamed System Exceptions
c) User-defined Exceptions
LOGO
TYPES OF EXCEPTION

PL/SQL
System exceptions are automatically
raised by Oracle, when a program
violates a RDBMS rule. There are some
system exceptions which are raised
frequently, so they are pre-defined and
given a name in Oracle which are known
as Named System Exceptions.
LOGO
NAMED SYSTEM EXCEPTIONS

PL/SQL
For example: NO_DATA_FOUND and
ZERO_DIVIDE are called Named System
exceptions.
Named system exceptions are:
1) Not Declared explicitly,
2) Raised implicitly when a predefined
Oracle error occurs,
3) caught by referencing the standard
name within an exception-handling
routine. LOGO

PL/SQL
Exception Name Reason(Message) Error Number
CURSOR_ALREADY_
OPEN
When you open a
cursor that is
already open.
ORA-06511
LOGO

PL/SQL
INVALID_CURSOR When you perform an
invalid operation on a
cursor like closing a
cursor, fetch data from
a cursor that is not
opened.
ORA-01001
NO_DATA_FOUND When a
SELECT...INTO
clause does not
return any row from
a table.
ORA-01403
LOGO

PL/SQL
TOO_MANY_ROWS
When you SELECT or
fetch more than one
row into a record or
variable.
ORA-01422
ZERO_DIVIDE When you attempt
to divide a number
by zero.
ORA-01476.
LOGO

PL/SQL
Create or Replace Procedure proc_excep(vdesg emp.job%type)
is
vename varchar2(20);
Begin
select ename into vename from emp
where job =vdesg;
dbms_output.put_line('Name:-' || vename);
Exception
when NO_DATA_FOUND then
dbms_output.put_line('No Employee existed with given job');
when TOO_MANY_ROWS then
dbms_output.put_line('Multiple employees existed ,use explicit
cursor');
End proc_excep;
/
LOGO
PROGRAM ON NAMED SYSTEM EXCEPTION

PL/SQL
Apart from system exceptions we can explicitly
define exceptions based on business rules. These
are known as user-defined exceptions.
Steps to be followed to use user-defined exceptions:
• They should be explicitly declared in the
declaration section.
• They should be explicitly raised in the Execution
Section.
• They should be handled by referencing the user-
defined exception name in the exception section.
LOGO
USER DEFINED EXCEPTIONS

PL/SQL
Declare
var_name Exception
Begin
Statement1
Statement2
Raise <var_name>;
Exception
When <var_name> then
Statement1
Statement2
End;
/
LOGO
SYNTAX OF USER DEFINED EXCEPTION

PL/SQL
Create or Replace Procedure proc_comm (veid int)
is
vcomm int;
c_miss Exception;
Begin
select comm into vcomm from emp where empno=veid;
if vcomm IS NOT NULL then
dbms_output.put_line('Comm of' || veid || 'is' || vcomm);
else
RAISE c_miss;
end if;
Exception
when NO_DATA_FOUND then
dbms_output.put_line('EmpId Not Existed');
when TOO_MANY_ROWS then
dbms_output.put_line('Duplicate EmpId');
when c_miss then
dbms_output.put_line('Comm is Not Existed');
End proc_comm;
LOGO
EXAMPLE ON USER DEFINED EXCEPTION

PL/SQL
 It is also known as PRAGMA EXCEPTION_INIT.
 It is the way to associate user defined exception
with oracle predefined error.
 If the oracle predefined error is not having name
then we can assign name to that error using
PRAGMA EXCEPTION_INIT.
LOGO
UNNAMED EXCEPTIONS

PL/SQL
DECLARE
user_define_exception_name EXCEPTION;
PRAGMA EXCEPTION_INIT(user_define_exception_name,-
error_number);
BEGIN
statement(s);
IF condition THEN
RAISE user_define_exception_name;
END IF;
EXCEPTION
WHEN user_define_exception_name THEN
User defined statement (action) will be taken;
END;
/
Points to Ponder:-
* exception_name and error_number define on yourself, where exception_name is
character string up to 2048 bytes support and error_number is a negative integer
range from -20000 to -20999.
LOGO
SYNTAX OF UNNAMED EXCEPTION

PL/SQL
DECLARE
myex EXCEPTION;
PRAGMA EXCEPTION_INIT(myex,-20015);
n NUMBER := &n;
BEGIN
FOR i IN 1..n LOOP
dbms_output.put_line(i);
IF i=n THEN
RAISE myex;
END IF;
END LOOP;
EXCEPTION
WHEN myex THEN
dbms_output.put_line('loop finish');
END;
/
LOGO
PROGRAM ON UNNAMED EXCEPTION

PL/SQL
 A cursor is a temporary work area created in the
system memory when a SQL statement is
executed. A cursor contains information on a
select statement and the rows of data accessed
by it.
 This temporary work area is used to store the
data retrieved from the database, and manipulate
this data. A cursor can hold more than one row,
but can process only one row at a time. The set of
rows the cursor holds is called the active set.
LOGO
Sub titleCursor in PL/SQL
DEFINITION OF CURSOR

PL/SQL
There are two types of cursors in PL/SQL:
 Implicit cursors
 Explicit cursors
LOGO
TYPES OF CURSOR

PL/SQL
 Managed by Oracle Engine
 Allocation and deallocation is done by Oracle
Engine.
 Used by DML,DQL.
LOGO
IMPLICIT CURSOR

PL/SQL
 SQL%ISOPEN
 SQL%FOUND
 SQL%NOTFOUND
 SQL%ROWCOUNT
LOGO
PROPERTIES OF IMPLICIT CURSOR

PL/SQL
Create or Replace procedure proc_sal_update(vjob in emp.job%type,incr in int)
is
Begin
update empcp
set sal=sal+((sal*incr)/100)
where job=vjob;
if (sql%found) then
dbms_output.put_line('Updation is Successful');
dbms_output.put_line('Number of '||vjob||'s updated:'
||SQL%ROWCOUNT);
else
dbms_output.put_line('Updation Failed');
dbms_output.put_line('Number of '||vjob||'s updated:'
||SQL%ROWCOUNT);
end if;
End proc_sal_update;
/
LOGO
PROGRAM ON IMPLICIT CURSOR

PL/SQL
 Managed by User
 Allocation and deallocation is done by User.
 To display multiple records using
subprogram/procedure.
Its has four steps to define it;-
I)Declare Cursor
II)Open Cursor
III)Fetch data from cursor
IV)Close Cursor
LOGO
EXPLICIT CURSOR

PL/SQL
I)Declare Cursor
CURSOR <cursor_name> IS select
column_name...... from <table_name>
where condition;
II)Open Cursor
OPEN <cursor_name>;
III)fetch data from Cursor
FETCH <cursor_name> INTO <var>
IV)Close Cursor
CLOSE <cursor_name>;
LOGO
SYNTAX OF EXPLICIT CURSOR

PL/SQL
 <cursor_name>%ISOPEN
 <cursor_name>%FOUND
 <cursor_name>%NOTFOUND
 <cursor_name>%ROWCOUNT
LOGO
PROPERTIES OF EXPLICIT CURSOR

PL/SQL
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
dbms_output.put_line(my_rec.wages||' '||my_rec.ename);
END IF;
END LOOP;
CLOSE my_cursor;
END;
/
LOGO
PROGRAM ON EXPLICIT CURSOR

PL/SQL
Triggers are stored programs, which are
automatically executed or fired when some
events occur. Triggers are, in fact, written to be
executed in response to any of the following
events −
*A database manipulation (DML) statement
(DELETE, INSERT, or UPDATE)
*A database definition (DDL) statement (CREATE,
ALTER, or DROP).
*A database operation (SERVERERROR, LOGON,
LOGOFF, STARTUP, or SHUTDOWN).
LOGO
Sub titleTrigger in PL/SQL
DEFINITION

PL/SQL
CREATE OR REPLACE TRIGGER display_salary_changes1
BEFORE DELETE OR INSERT OR UPDATE ON empcp1
FOR EACH ROW
WHEN (old.deptno > 0)
DECLARE
sal_diff number;
BEGIN
sal_diff := :NEW.sal - :OLD.sal;
dbms_output.put_line('Old salary: ' || :OLD.sal);
dbms_output.put_line('New salary: ' || :NEW.sal);
dbms_output.put_line('Salary difference: ' || sal_diff);
END;
/
LOGO
PROGRAM ON DML CURSOR

PL/SQL
CREATE [OR REPLACE ] TRIGGER trigger_name
{BEFORE | AFTER | }
{INSERT [OR] | UPDATE [OR] | DELETE}
[OF col_name]
ON table_name
[REFERENCING OLD AS o NEW AS n]
[FOR EACH ROW]
WHEN (condition)
DECLARE
Declaration-statements
BEGIN
Executable-statements
EXCEPTION
Exception-handling-statements
END
LOGO
SYNTAX OF TRIGGER

DAC training-batch -2020(PLSQL)

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