PL/SQL - IF-THEN-ELSIF Statement

The IF-THEN-ELSIF statement allows you to choose between several alternatives. An IF-THEN statement can be followed by an optional ELSIF...ELSE statement. The ELSIF clause lets you add additional conditions.

When using IF-THEN-ELSIF statements there are a few points to keep in mind.

• It's ELSIF, not ELSEIF.

• An IF-THEN statement can have zero or one ELSE's and it must come after any ELSIF's.

• An IF-THEN statement can have zero to many ELSIF's and they must come before the ELSE.

• Once an ELSIF succeeds, none of the remaining ELSIF's or ELSE's will be tested.

Syntax

The syntax of an IF-THEN-ELSIF Statement in PL/SQL programming language is −

IF(boolean_expression 1)THEN  
   S1; -- Executes when the boolean expression 1 is true  
ELSIF( boolean_expression 2) THEN 
   S2;  -- Executes when the boolean expression 2 is true  
ELSIF( boolean_expression 3) THEN 
   S3; -- Executes when the boolean expression 3 is true  
ELSE  
   S4; -- executes when the none of the above condition is true  
END IF; 

Example

DECLARE 
   a number(3) := 100; 
BEGIN 
   IF ( a = 10 ) THEN 
      dbms_output.put_line('Value of a is 10' ); 
   ELSIF ( a = 20 ) THEN 
      dbms_output.put_line('Value of a is 20' ); 
   ELSIF ( a = 30 ) THEN 
      dbms_output.put_line('Value of a is 30' ); 
   ELSE 
       dbms_output.put_line('None of the values is matching'); 
   END IF; 
   dbms_output.put_line('Exact value of a is: '|| a );  
END; 
/ 

When the above code is executed at the SQL prompt, it produces the following result −

None of the values is matching 
Exact value of a is: 100  

PL/SQL procedure successfully completed.