MySQL WHERE NOT IN skip NULL?

Question

MySQL

The table table has a status field which can be NULL.

SELECT * FROM `table` WHERE `status` NOT IN ('cancel', 'finished', 'failed');

This query will not return fields where status is NULL unless you explicitly specify OR status IS NULL.

Bug or feature?

The question is rather for your own understanding of the logic of such an implementation of the WHERE NOT IN condition.

Answer 1

This is not a bug. Comparison with NULL gives undefined result, so you can't check equality/inequality with NULL by normal means