Subject Re: [firebird-support] Re: Conditional conundrum
Author Ann W. Harrison
Rick Debay wrote:

> Is this legal for Firebird? In the stored procedure it would resolve to
> Where
> (unit_use in ('U') and 'X' = 'U') or
> (unit_use not in ('U') and 'X' not ='U')
> If the parameter passed to the stored procedure was 'X'. From
> experience and previous discussions, the planner has problems with
> statements like this (the most discussed conditional that gives the
> planner a fit is NULL IS NULL).

NULL is a separate discussion, which has been held more time than
I can bear to contemplate.

Firebird can certainly handle 'X' = 'U', though it does not currently
recognize the tautology and checks each candidate row.