Re: Three valued logic (again)

David Williams <djw@smooth1.demon.co.uk> wrote: ...very good explanations sniped... : PPS All this is my theories based on the fact that SQL is really : all about sets and set theory...Remember A n B...A u B etc?.. : i.e. the only thing I am really sure about is the fact that SQL : is set based since that is what my university course thought me, I am very sorry to say this David, but if this is what you where realy told in that university course, they have told you a blatant lie. SQL is based on multisets, not sets. The difference is quite large, and the theory of sets doesn't allways quite apply. You do apperantly have a very good grasp of the whole thing anyway though :-) Nils.Myklebust@idg.no NM Data AS, P.O.Box 9090 Gronland, N-0133 Oslo, Norway My opinions are those of my company The Informix FAQ is at http://www.iiug.org