help you fix your problem It is a good idea if there is a one-to-one mapping of login and signup information. You get better performance with one id lookup. Maybe a "Users" table? On a sidenote, I hope by "password" is not a clear text password field and is instead a hash of the password. You should never have clear text passwords stored anywhere.
I wish this help you The problem stems from a limitation in T-SQL itself. From this Error message 1795 "a table cannot appear more than one time in a list of all the cascading referential actions that are started by either a DELETE or an UPDATE statement. The solution is to use triggers on the lookup table to simulate an update cascade for the remaining relationships.
How can I make mysql "num_rows" work in "SELECT TABLE_NAME FROM information_schema.TABLES"?