There are three different syntaxes for these types of statements.
Syntax #1: IF-THEN
IF condition THEN
{...statements...}
END IF;
Syntax #2: IF-THEN-ELSE
IF condition THEN
{...statements...}
ELSE
{...statements...}
END IF;
Syntax #3: IF-THEN-ELSIF
IF condition THEN
{...statements...}
ELSIF condition THEN
{...statements...}
ELSE
{...statements...}
END IF;
Here is an example of a function that uses the IF-THEN-ELSE statement:
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 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.