I wish to turn cascade on automatically. How do i do this in MySQL?
Ideally Let me edit my.cnf
You cannot switch it on automatically.
You will need to place it like a foreign key constraint on the key-by-key basis. Begin to see the documentation at http://dev.mysql.com/doc/refman/5.5/en/innodb-foreign-key-constraints.html
The cascade on remove behavior is controlled once the individual foreign key constraints are produced. There's no global setting with this.