On 4/26/05, Jigal van Hemert wrote: > From: "Jochem van Dieten" >>> Why is this? >> >> Because the SQL standard says so. > > A true observation, but still no explanation or reason why ;-P
I consider it a good enough explanation of why MySQL doesn't allow it. As to why the SQL standard doesn't allow it: NULL doesn't fit particularly well in relational theory and there has probably been considerable pressure from certain vendors (imagine the problems when an empty string is indistinguishable from a NULL so both '' = '' and NULL <> NULL must be true, but now not just for some wacky varchar but for your primary key). Just speculation of course :) Jochem -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
