PL/SQL If

PL/SQL supports the programming language features like conditional statements and iterative statements. Its programming constructs are similar to how you use in programming languages like Java and C++.

Syntax for IF Statement:

There are different syntaxes for the IF-THEN-ELSE statement.

Syntax: (IF-THEN statement):

IF condition 
THEN 
Statement: {It is executed when condition is true}
END IF;

This syntax is used when you want to execute statements only when condition is TRUE.

Syntax: (IF-THEN-ELSE statement):

IF condition 
THEN
   {...statements to execute when condition is TRUE...}
ELSE
   {...statements to execute when condition is FALSE...}
END IF; 

This syntax is used when you want to execute one set of statements when condition is TRUE or a different set of statements when condition is FALSE.

Syntax: (IF-THEN-ELSIF statement):

IF condition1 
THEN
   {...statements to execute when condition1 is TRUE...}
ELSIF condition2 
THEN
   {...statements to execute when condition2 is TRUE...}
END IF;

This syntax is used when you want to execute one set of statements when condition1 is TRUE or a different set of statements when condition2 is TRUE.

Syntax: (IF-THEN-ELSIF-ELSE statement):

IF condition1 
THEN
   {...statements to execute when condition1 is TRUE...}
ELSIF condition2 
THEN
   {...statements to execute when condition2 is TRUE...}
ELSE
   {...statements to execute when both condition1 and condition2 are FALSE...}
END IF;

It is the most advance syntax and used if you want to execute one set of statements when condition1 is TRUE, a different set of statement when condition2 is TRUE or a different set of statements when both the condition1 and condition2 are FALSE.

When a condition is found to be TRUE, the IF-THEN-ELSE statement will execute the corresponding code and not check the conditions any further.

If there no condition is met, the ELSE portion of the IF-THEN-ELSE statement will be executed.

ELSIF and ELSE portions are optional.

Example of PL/SQL If Statement

Let's take an example to see the whole concept:

DECLARE
   a number(3) := 500;
BEGIN
   -- check the boolean condition using if statement 
   IF( a < 20 ) THEN
      -- if condition is true then print the following  
      dbms_output.put_line('a is less than 20 ' );
   ELSE
      dbms_output.put_line('a is not less than 20 ' );
   END IF;
   dbms_output.put_line('value of a is : ' || a);
END;

After the execution of the above code in SQL prompt, you will get the following result:

a is not less than 20
value of a is : 500
PL/SQL procedure successfully completed.