The relational model was designed using a 3 valued logic - true, false,null.
All relational database implementations will inflict this on you :-)
Not everyone is convinced that the 3 valued approach was the best way.
For some entertaining comments by Chris Date and Fabian Pascal see:
http://www.dbdebunk.citymax.com/page/page/622689.htm
best wishes
Mark
Baldur Norddahl wrote:
>Hi,
>
>How come "X=null" is not the same as "X is null"? I got a few selects with
>queries like this:
>
>
>