1.会员表member和车辆表car,更新每个会员下面的车辆数量have_car字段。
DELIMITER $$ USE $$ DROP PROCEDURE IF EXISTS `sp_update_member_have_car`$$ CREATEPROCEDURE `sp_update_member_have_car`()
BEGIN
DECLARE tmp INT DEFAULT 0;
DECLARE done INT DEFAULT -1; /* 声明游标 */
DECLARE myCursor CURSOR FOR SELECT reg_no FROM member WHERE have_car IS NULL; /* 当游标到达尾部时,mysql自动设置done=1 */
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done=1; /* 打开游标 */
OPEN myCursor; /* 循环开始 */
myLoop: LOOP
/* 移动游标并赋值 */
FETCH myCursor INTO tmp;
IF done = 1 THEN
LEAVE myLoop;
END IF;
/* do something */
UPDATE member SET have_car = (SELECT COUNT(*) FROM car WHERE mem_no= tmp ) WHERE reg_no = tmp;
/* 循环结束 */
END LOOP myLoop; /* 关闭游标 */
CLOSE myCursor;
END$$ DELIMITER ;
建立执行计划,每天凌晨1点执行存储过程。
DELIMITER $$ ALTER EVENT `E_Update_HaveCar_Field_Event_1` ON SCHEDULE EVERY 1 DAY STARTS '2014-09-19 01:00:00' ON COMPLETION PRESERVE ENABLE DO BEGIN
CALL `sp_update_member_have_car`();
END$$ DELIMITER ;