MySQL 存储过程和"Cursor"的使用方法
时间：2021-03-05 12:41:16|栏目：Mysql|点击： 次
示例如下：
CREATE PROCEDURE `justifyGroupNum`()
NOT DETERMINISTIC
SQL SECURITY DEFINER
COMMENT ''
BEGIN
/*how to run:call justifyGroupNum()*/
DECLARE p_group_id int;
declare p_num int;
declare stopFlag int;
DECLARE cursor_name CURSOR
FOR select c_group_id,count(*) as num
from `t_group_member`
where c_valid in (3,4)
group by c_group_id;
DECLARE CONTINUE HANDLER FOR NOT FOUND set stopFlag=1;
OPEN cursor_name;
REPEAT
FETCH cursor_name INTO p_group_id,p_num;
begin
update t_groupinfo set c_member_number=p_num where c_group_id=p_group_id;
end;
UNTIL stopFlag = 1
END REPEAT;
CLOSE cursor_name;
END;
总结：
1、注意设置游标的countinue handler：DECLARE CONTINUE HANDLER FOR NOT FOUND set stopFlag=1;
2、注意REPEAT和UTILE [停止条件] END REPEAT的使用，否则不会循环；
3、如何RUN，输入并执行：call justifyGroupNum()
复制代码 代码如下:
CREATE PROCEDURE `justifyGroupNum`()
NOT DETERMINISTIC
SQL SECURITY DEFINER
COMMENT ''
BEGIN
/*how to run:call justifyGroupNum()*/
DECLARE p_group_id int;
declare p_num int;
declare stopFlag int;
DECLARE cursor_name CURSOR
FOR select c_group_id,count(*) as num
from `t_group_member`
where c_valid in (3,4)
group by c_group_id;
DECLARE CONTINUE HANDLER FOR NOT FOUND set stopFlag=1;
OPEN cursor_name;
REPEAT
FETCH cursor_name INTO p_group_id,p_num;
begin
update t_groupinfo set c_member_number=p_num where c_group_id=p_group_id;
end;
UNTIL stopFlag = 1
END REPEAT;
CLOSE cursor_name;
END;
总结：
1、注意设置游标的countinue handler：DECLARE CONTINUE HANDLER FOR NOT FOUND set stopFlag=1;
2、注意REPEAT和UTILE [停止条件] END REPEAT的使用，否则不会循环；
3、如何RUN，输入并执行：call justifyGroupNum()
