MySQL + SQL · Lesson 61

IFNULL and COALESCE in MySQL

Handling NULL Values

IFNULL and COALESCE replace NULL with a default value, so reports look clean.

IFNULL(value, default)

SELECT name, IFNULL(phone, 'Not given') AS phone
FROM students;

If phone is NULL, it shows "Not given" instead.

COALESCE(a, b, c, ...)

Returns the first non-NULL value from the list.

SELECT COALESCE(mobile, landline, 'No contact') AS contact
FROM students;

Summary

IFNULL replaces NULL with one default.
COALESCE picks the first non-NULL from many options.