本文中的存储过程示例，预计的循环次数是yh表行数，由于SELECT IID INTO PINT FROM YH WHERE 0=1;不返回任何行，所以at_end后会立刻等于1（只循环一次就退出）。
DECLARE at_end INT DEFAULT 0;
DECLARE PIID INTEGER DEFAULT 0 ;
DECLARE PINT INTEGER DEFAULT 0 ;
DECLARE not_found CONDITION FOR SQLSTATE '02000';
--DECLARE PCOUNT INTEGER;
DECLARE c1 CURSOR FOR
SELECT IID FROM YH;
DECLARE CONTINUE HANDLER FOR not_found
SET at_end = 1;
OPEN c1;
SET PCOUNT=0;
ins_loop:
LOOP
FETCH c1 INTO PIID;
IF at_end <>0 THEN
LEAVE ins_loop;
END IF;
SET PCOUNT=PCOUNT+1;
SELECT IID INTO PINT FROM YH WHERE 0=1;
END LOOP;
