I'm no database expert so I don't relly know about this. However, quoted from the official MySQL reference manual :
A PRIMARY KEY is a unique KEY with the extra constraint that all key columns must be defined as NOT NULL. In MySQL the key is named PRIMARY. A table can have only one PRIMARY KEY. If you don't have a PRIMARY KEY and some applications ask for the PRIMARY KEY in your tables, MySQL will return the first UNIQUE key, which doesn't have any NULL columns, as the PRIMARY KEY. (6.5.3 CREATE TABLE Syntax) Tom --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
