Rule Definition
Comparisons with Null can never result in either True or False, but always in a third logical result, Unknown.

Remediation
To test for NULL, use the IS NULL and IS NOT NULL operators.

Violation Code Sample

SELECT AuthName FROM Authors WHERE AuthId = NULL

Fixed Code Sample

SELECT AuthName FROM Authors WHERE AuthId IS NULL

MySQL Documentation : https://dev.mysql.com/doc/refman/8.0/en/working-with-null.html PostgreSQL Documentation : https://www.postgresql.org/docs/9.1/functions-comparison.html Oracle Documentation : https://docs.oracle.com/database/121/SQLRF/sql_elements005.htm#SQLRF30037 SQL Server Documentation : https://docs.microsoft.com/fr-fr/sql/t-sql/language-elements/null-and-unknown-transact-sql?view=sql-server-2017