How to make an efficient check constraint for an e-mail field in Firebird

Question

How to make an efficient check constraint for an e-mail field in Firebird (if field value not null)?

Answer 1

You could use the SIMILAR TO operator to test against regular expression pattern, something like

CHECK(emailfield SIMILAR TO '[[:ALNUM:]._%+-]+@[[:ALNUM:].-]+\.[[:ALPHA:]]+')