How do NULL values behave in comparison operations?

Parthiban Kannan

Updated on January 8, 2026

< 1 min read

NULL values are treated as unknown in comparisons.
Any direct comparison like =, <, or > with NULL returns false or unknown.
IS NULL or IS NOT NULL must be used to check for NULLs.
In my project, we filtered customers with missing emails using IS NULL.
Aggregates like SUM or AVG ignore NULLs automatically.
Failure to handle NULLs can lead to missing or incorrect results.
Proper handling ensures accurate filtering and calculations.