mysql - How to add multiple primary keys in a single table -

i tried create table fillowing in phpmyadmin. gives error:

"#1075 - incorrect table definition; there can 1 auto column , must defined key"

please 1 me

create table itemlist (     uid varchar(15),     item_id int auto_increment,     item_name varchar(50) not null,     primary key (uid, item_id) );