Exactly the point. Michael, NULL *is* information. It means "unknown" and that is in itself useful information. A common example:
A new employee is hired but which department she will work in is unknown. So the data entry person enters all the known information and leaves the rest until it has been clarified. The alternative is even worse than the so-called NULL problem and the alleged difficulty of querying against NULLable columns: in a case like that described above, the only way to handle it is to create a fake row in the foreign-key table, for "Department Zero" or somesuch. That immediately turns every query into a more complex beast that it would otherwise have been. Every single query must exclude this "zeroth" row; join a few tables all exhibiting this problem and things get really crazy. Not to mention the fact that these "zeroth" rows falsify reality and combine fiction with fact. Even worse, the "-99999" approach means that you can't impose a constraint on the column (such as "must be a positive integer". And finally, I cannot believe that you really mean "no NULLS ever". Surely you mean only FKs. Otherwise, how would you handle fax numbers for people with no fax, or middle names for people with none? Arthur >
