PL/SQL - Control Statements

PL/SQL - Control Statements

Control Statements are used to ramdom execution of the program .In PLSQL lamguage these are classified into following types.

1.Conditional Statements
2.Looping Statements
3.Unconditional Statements

Conditional Statements

Conditional statements are used check the condition whether it is true or false.
In PLSQL language these opeatrs are classified into following types.

1.IF - THEN statement
2.IF-THEN-ELSE statement
3.IF-THEN-ELSIF statement
4.nested IF-THEN-ELSE
5.Case statement
6.Searched CASE statement

IF - THEN statement

'if- then' is a keyword in PLSQL language .Which is used to execute one block of statements by negleting some other statements.
Syntax:

if(Condition) then
...
...
...
end if;

In the above syntax 'if' condition is true the statements of 'if' block is execute.'if' the condition is false program terminated.

Example #1

DECLARE 
   a number(2) := 10; 
BEGIN 
   IF( a < 20 ) THEN 
      
      dbms_output.put_line('a is less than 20' ); 
   END IF; 
   dbms_output.put_line('value of a is : ' || a); 
END; 
/

Example #2

DECLARE 
   c_id customers.id%type := 1; 
   c_sal  customers.salary%type; 
BEGIN 
   SELECT  salary  
   INTO  c_sal 
   FROM customers 
   WHERE id = c_id; 
   IF (c_sal <= 2000) THEN 
      UPDATE customers  
      SET salary =  salary + 1000 
         WHERE id = c_id; 
      dbms_output.put_line ('Salary updated'); 
   END IF; 
END; 
/