Change unique key together in mysql

Question

I have in my MYSQL table a unique key and i want to add to it.

UNIQUE KEY `user_id` (`user_id`,`account_id`)

and i want to add another

UNIQUE KEY `user_id` (`user_id`,`account_id`,`pet_id`)

Answer 1

ALTER TABLE your_table 
   DROP INDEX user_id, 
   ADD UNIQUE KEY `user_id` (`user_id`,`account_id`,`pet_id`)