You can have an auto-Incrementing column that is not the PRIMARY KEY
, as long as there is an index (key) on it:
CREATE TABLE members (
id int(11) UNSIGNED NOT NULL AUTO_INCREMENT,
memberid VARCHAR( 30 ) NOT NULL ,
`time` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ,
firstname VARCHAR( 50 ) NULL ,
lastname VARCHAR( 50 ) NULL ,
PRIMARY KEY (memberid) ,
KEY (id) --- or: UNIQUE KEY (id)
) ENGINE = MYISAM;