按照用户ID进行分组,保留用户的最新的1000条数据,超过1000条的都

BEGIN
	#Routine body goes here...
	/*
	查询用户超过1000条则进行删除功能
	 */
	DECLARE act_friends_user_id INT;
	DECLARE act_friends_min_id INT;
	DECLARE dn INT default 0;
	/*定义查询语句*/
	DECLARE act CURSOR FOR SELECT user_id FROM act_friends GROUP BY user_id HAVING COUNT(user_id) > 1000; 
	DECLARE EXIT HANDLER FOR NOT FOUND set dn=1;
	/*开始进行循环*/
	OPEN act;
	act_loop:LOOP
	FETCH act INTO act_friends_user_id;
	/*循环到最后查找不到条件则跳出这个游标循环*/
	if dn=1 THEN
	LEAVE act_loop;
	END if;
	/*获取最新1000条数据中的最小ID值*/
	select min(id) into act_friends_min_id from (select id from act_friends where user_id =act_friends_user_id ORDER BY date DESC limit 1000) as temp;
	SELECT act_friends_min_id;
	DELETE FROM act_friends where user_id = act_friends_user_id AND id < act_friends_min_id;
	END LOOP;
	CLOSE act;
END