Thanks Martijn - that is a clear explanation of the philosophy. I did not get it from the examples and the manual.
Doug On Mon, 19 Sep 2005, Martijn Tonies wrote: > Hello Doug, > > > > My question question from MySQL 4.0.22: is it okay that a null interger > > tests as > > equal to any value. I am not sure the table structure matters but in case > it is [cut]> > That's because NULL is NOT a value (not the logical "not" ;) ... It's a > state. > > Any column can have two states: either NULL or NOT NULL. > > When a column is "not null" it can have values suitable for it's given > domain > (eg: all integer values). > > If there's no value (NULL), how can you compare it? > > Think of "NULL" as "unknown". Is 2 equal to "unknown"? I don't know, so > the result is "unknown", hence, NULL. > > > Hope this helps, > > With regards, > > Martijn Tonies > Database Workbench - tool for InterBase, Firebird, MySQL, Oracle & MS SQL > Server > Upscene Productions > http://www.upscene.com > Database development questions? Check the forum! > http://www.databasedevelopmentforum.com > _____ Douglas Denault http://www.safeport.com [EMAIL PROTECTED] Voice: 301-469-8766 Fax: 301-469-0601 -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
