Hi, RE: > And columns in primary keys must be NOT NULL. Columns in unique > keys can be NULL (if they are NOT NULL, then the unique key is > functionally the same as a primary key).
OK, thanks guys for the explanation. Then the result of mysqldump table definition part: UNIQUE KEY HONstid (HONstid,HONname) means that I have two unique keys: HONstid and also the (HONstid,HONname) combination? This does not make too much sense; if I can have only one HONstid in my table, then of course i can have only one kind of (HONstid,HONname) combination. In the actual table, I have multiple occurences of values (HONstid,HONname)in the HONstid column, i.e. it does not seem like HONstid in itself was a unique key. Only the (HONstid,HONname) combination is unique. Cheers Gaspar p.s.: Paul, I very much enjoy your MySQL book. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
