Subject Does Firebird support deferred constraints?
Author Thomas Kellerer

I can't find a complete SQL reference for all statements and it's very
hard to incrementally scan all the release notes, so I might have
missed something.

We are trying to add support for Firebird to an application that
currently runs on Postgres and Oracle and that makes use of deferred

Given the fact that Firebird tries to be ANSI compliant as much as
possible, it's hard to believe that deferred constraints are not
supported (which are defined in SQL92 to my knowledge)