MySQL can only set a self-growing field

MySQL error: There can be is only one auto column and it must is defined as a key

The reason is that you have a field a set auto_increment, another field B is also set as the primary key, this is wrong, because MySQL will automatically grow the field as the main key, so according to this logic, your table has two primary key, so the method is to remove the primary key index of the B field, If you mean that you want the data in the B field to be non-repeatable, you can use unique to limit it.

MySQL can only set a self-growing field