I would use a composite (multi-column) key. CREATE TABLE INFO ( t1ID INT, t2ID INT, PRIMARY KEY (t1ID, t2ID) ) This way you can have t1ID and t2ID as foreign keys pointing to their respective tables as well.
A Table can have a Composite Primary Key which is a primary key made from two or more columns. For example: CREATE TABLE userdata ( userid INT, userdataid INT, info char(200), primary key (userid, userdataid) ); Update: Here is a link with a more detailed description of composite primary keys.
According to the documentation, it’s CREATE TABLE something ( column1, column2, column3, PRIMARY KEY (column1, column2) );