Re: The BOOLEAN data type

From: --CELKO-- <71062.1056_at_compuserve.com>
Date: 2 Apr 2003 17:51:38 -0800
Message-ID: <c0d87ec0.0304021751.ff4f015@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 Wed Apr 02 2003 - 19:51:38 CST