Oracle / PLSQL: IF-THEN-ELSE Statement

This Oracle tutorial explains how to use the IF-THEN-ELSE statement in Oracle with syntax and examples.

Description

In Oracle, the IF-THEN-ELSE statement is used to execute code when a condition is TRUE, or execute different code if the condition evaluates to FALSE.

Syntax

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

Syntax (IF-THEN)

The syntax for IF-THEN in Oracle/PLSQL is:

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

You use the the IF-THEN syntax, when you want to execute statements only when condition is TRUE.

Syntax (IF-THEN-ELSE)

The syntax for IF-THEN-ELSE in Oracle/PLSQL is:

IF condition THEN
   {...statements to execute when condition is TRUE...}

ELSE
   {...statements to execute when condition is FALSE...}

END IF;

You use the IF-THEN-ELSE syntax, 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)

The syntax for IF-THEN-ELSIF in Oracle/PLSQL is:

IF condition1 THEN
   {...statements to execute when condition1 is TRUE...}

ELSIF condition2 THEN
   {...statements to execute when condition1 is FALSE and condition2 is TRUE...}

END IF;

You use the IF-THEN-ELSIF syntax, 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)

The syntax for IF-THEN-ELSIF-ELSE in Oracle/PLSQL is:

IF condition1 THEN
   {...statements to execute when condition1 is TRUE...}

ELSIF condition2 THEN
   {...statements to execute when condition1 is FALSE and condition2 is TRUE...}

ELSE
   {...statements to execute when both condition1 and condition2 are FALSE...}

END IF;

You use the IF-THEN-ELSIF-ELSE syntax, when you want to execute one set of statements when condition1 is TRUE, a different set of statements when condition2 is TRUE, or a different set of statements when all previous conditions (ie: condition1 and condition2) are FALSE.

Note

• Once a condition is found to be TRUE, the IF-THEN-ELSE statement will execute the corresponding code and not evaluate the conditions any further.
• If no condition is met, the ELSE portion of the IF-THEN-ELSE statement will be executed.
• It is important to note that the ELSIF and ELSE portions are optional.

Example

The following is example using the IF-THEN-ELSE statement in an Oracle function:

CREATE OR REPLACE Function IncomeLevel
   ( name_in IN varchar2 )
   RETURN varchar2
IS
   monthly_value number(6);
   ILevel varchar2(20);

   cursor c1 is
     SELECT monthly_income
     FROM employees
     WHERE name = name_in;

BEGIN

   open c1;
   fetch c1 into monthly_value;
   close c1;

   IF monthly_value <= 4000 THEN
      ILevel := 'Low Income';

   ELSIF monthly_value > 4000 and monthly_value <= 7000 THEN
      ILevel := 'Avg Income';

   ELSIF monthly_value > 7000 and monthly_value <= 15000 THEN
      ILevel := 'Moderate Income';

   ELSE
      ILevel := 'High Income';

   END IF;

   RETURN ILevel;

END;

In this IF-THEN-ELSE statement example, we've created a function called IncomeLevel. It has one parameter called name_in and it returns a varchar2. The function will return the income level based on the employee's name.