tony yau wrote: | Hi All | | Thanks for all your comments on my previous mail, very much appreciated. | I'm stuck again! | I've created the following lookup table for m <-> m relationship between | a Group and a Contact table. | | CREATE TABLE Group_Contact( | GroupID INT NOT NULL, | ContactID INT NOT NULL, | | Index (GroupID), | FOREIGN KEY (GroupID) REFERENCES Group (PKey) ON DELETE CASCADE, | Index (ContactID), | FOREIGN KEY (ContactID) REFERENCES Contact (PKey) ON DELETE CASCADE | ) TYPE=InnoDB COMMENT='Group to Contact lookup'; | | what do I need to do to ensure only unique (GroupID,ContactID) pair can be | inserted into the table?
This question is really a MySQL question. You might want to join their mailing list as you'll get better answers for this type of question there.
That said: The easiest way would be to make GroupId, ContactID a unique index. In this case, primary key would be OK. Add the statement
Primary Key(GroupID, ContactId),
just before the first "Index" statement.
-- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
