Mysql报错：1172 - Result consisted of more than one row

执行mysql函数时报错：1172 - Result consisted of more than one row

函数语句中select into语句中WHERE account = userName查出的结果出现2条相同的记录才报出这个错误

SELECT id,last_stamp,token INTO userID,lastStamp2,tokenStr2 FROM game_user WHERE account = userName;