juniorMySQL
Handling NULL values
Updated May 4, 2026
Short answer
Use IS NULL, IS NOT NULL, or the COALESCE() function.
Deep explanation
NULL represents an unknown value. Standard operators like '=' or '!=' do not work with NULL; specific keywords are required.
Real-world example
Checking if a user has not provided an optional phone number.
Common mistakes
- Using 'WHERE column = NULL', which will always return an empty result.
Follow-up questions
- What does COALESCE(val, 0) do?