Either OR non-null constraints in MySQL

Question

What\'s the best way to create a non-NULL constraint in MySQL such that fieldA and fieldB can\'t both be NULL. I don\'t care if either one is NULL by itself, just as long as the

Answer 1

This isn't an answer directly to your question, but some additional information.

When dealing with multiple columns and checking if all are null or one is not null, I typically use COALESCE() - it's brief, readable and easily maintainable if the list grows:

COALESCE(a, b, c, d) IS NULL -- True if all are NULL

COALESCE(a, b, c, d) IS NOT NULL -- True if any one is not null

This can be used in your trigger.