Re: The BOOLEAN data type
Date: 2 Apr 2003 17:51:38 -0800
Message-ID: <c0d87ec0.0304021751.ff4f015_at_posting.google.com>
>> What would the semantic difference between NULL and UNKNOWN be? <<
NULL is a marker for a value; UNKNOWN is a logical value.
>> I would say "Booleans are sometimes, but not usually, a sign of bad
programming". <<
My experience has been "usually" -- the programs I have seen are still thinking in terms of assembly and 'C' level programming. People really do things like BOOLEAN gender! Yes, there are two-valued attributes in reality, but it is better to use a domain that it immediately obvious to a human reader -- most of the time we settle for sex IN ('m', 'f') instead of TRUE/FALSE (see my other post about the ISO gender codes).
>> Bad designers will just go ahead and misuse a NUMBER or VARCHAR
column instead anyway. <<
Amen. Received on Thu Apr 03 2003 - 03:51:38 CEST