PL/SQL - IF-THEN-ELSE Statement

A sequence of IF-THEN statements can be followed by an optional sequence of ELSE statements, which executes when the condition is FALSE.

Syntax:

Syntax for the IF-THEN-ELSE statement is:

IF condition THEN
   S1; 
ELSE 
   S2;
END IF;

Where, S1 and S2 are different sequence of statements. In the IF-THEN-ELSE statements, when the test condition is TRUE, the statement S1 is executed and S2 is skipped; when the test condition is FALSE, then S1 is bypassed and statement S2 is executed, For example,

IF color = red THEN
  dbms_output.put_line('You have chosen a red car')
ELSE
  dbms_output.put_line('Please choose a color for your car');
END IF;

If the boolean expression condition evaluates to true then the if-then block of code will be executed otherwise the else block of code will be executed.

Flow Diagram:

Example:

Let us try a complete example that would illustrate the concept:

DECLARE
   a number(3) := 100;
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;
/

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

a is not less than 20
value of a is : 100

PL/SQL procedure successfully completed.