A constraint to prevent the insert of an empty string in MySQL

Question

In this question I learned how to prevent the insert of a NULL value. But, unfortunately, an empty string is being inserted anyway. Apart from preventing this on the PHP sid

Answer 1

Normally you would do that with CHECK constraint:

foo_test VARCHAR(50) NOT NULL CHECK (foo_test <> '')

Prior to Version 8.0 MySQL had limited support for constraints. From MySQL Reference Manual:

The CHECK clause is parsed but ignored by all storage engines.

If you must stick to an old version use triggers as a workaround, as people have pointed out.

In future, you may want to take a look at PostgreSQL, which is considered to have better support for data integrity (among other things) by many people.