You will have to UPDATE to NULL those fields, modify the aplication to enter NULL instead of empty-string... Then add the UNIQUE INDEX...
In MySQL (unless modified) the dafault is that NULL values are incomparable thus allowing the creation of a UNIQUE INDEX. -- -- -- -- -- -- -- -- -- -- -- -- -- -- Gabriel PREDA Senior Web Developer -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
