Re: Re Wher != and NULLS

> Peter Wages wrote: > > > > Thanks Jonathan and Jack - > > > > Doesn't NULL mean the absence of value. That is different from > > unknown . Unknown implies that a field has a value, except nobody > > knows > > what it is. Absence of value means that something definetly has no > > value. > > > > To say something is unknown involves religion and GOD. Databases > > don't > > get into that sort of stuff. > > > > ciao > > p > > > > > > Tim Schaefer replied > > One of the nicest little discussions on NULL with INFORMIX data bases > was written > by Mark Sobel in his book, "Building Applications Using a 4GL". If I > am not > mistaken, NULL in 4GL should be treated as a garbage value, and not the > '\\0' > we think of in C. > I think you'll find that NULL means the absence of a value AND don't know. If a column has never had a value put into it it will have a NULL value. Similarly if a field on a FORM does not have a value entered into it then it is left NULL but in this case no answer was provided but the question was asked so it must mean DON'T KNOW. Malcolm Weallans Online Database Consultancy Phone 01628-72154 Fax 01628-37463 CIX - onlinedbc