📊 Conditional Functions in SQL

Last Updated: January 2026

The CONDITIONAL FUNCTION is a function that returns a value based on a condition.

Most Common Conditional Functions:

IF()

Returns a value based on a condition.

/*
IF(condition, value_if_true, value_if_false)
*/

SELECT IF(10 > 5, 'Greater', 'Lesser');
-- Output: Greater

CASE Statement

Returns a value based on multiple conditions.

/*
CASE
    WHEN condition1 THEN value1
    WHEN condition2 THEN value2
    ...
    ELSE value_default
END
*/

SELECT CASE
    WHEN 10 > 5 THEN 'Greater'
    WHEN 10 < 5 THEN 'Lesser'
    ELSE 'Equal'
END;
-- Output: Greater

IFNULL()

Replace NULL values with another value.

/*
IFNULL(column_name, condition, value_if_null)
*/

SELECT IFNULL(NULL, 10); -- Output: 10
SELECT IFNULL(5, 10); -- Output: 5

NULLIF()

Returns the first argument if it is not equal to the second argument, otherwise returns NULL.

SELECT NULLIF(10, 10); -- Output: NULL
SELECT NULLIF(10, 5); -- Output: 10

COALESCE()

Returns the first non-NULL argument.

SELECT COALESCE(NULL, NULL, 10); -- Output: 10
SELECT COALESCE(NULL, 5, 10); -- Output: 5
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