Setting one field of Composite primary key to AUTO_INCREMENT

Question

How to set one of the field of a primary key(composed of two fields of data type varchar(10) and int) of int data type to AUTO_INCREMENT, after declaring the primary key. Can we do it using ALTER command?

Answer 1

ALTER TABLE mytable ADD PRIMARY KEY( id, name);

ALTER TABLE mytable CHANGE id id INT(11) NOT NULL AUTO_INCREMENT;