mysql过程游标

DELIMITER $$
DROP PROCEDURE IF EXISTS `heli`.`prodtest` $$
CREATE PROCEDURE `heli`.`prodtest` ()
BEGIN
  /*局部变量的定义 declare*/
  declare pid varchar(45) default '';
  declare pq int default 0;
  declare pk double default 0.0;
  declare cur1 CURSOR FOR SELECT product_id,product_quantity,product_kg from productstock;
  /* 游标异常后设置pid为NULL */
  declare CONTINUE HANDLER FOR SQLSTATE '02000' SET pid = null;
  /*开游标*/
     OPEN cur1;
        FETCH cur1 INTO pid,pq,pk;
        WHILE (pid is not null) DO
            /* dosomething */
            select pid,pq,pk;
            FETCH cur1 INTO pid,pq,pk;
        END WHILE;
     CLOSE cur1;
END $$
DELIMITER ;