执行计划DESC SELECT COUNT(id) FROM room_break_history WHERE `create_time` BETWEEN '2017-02-20 04:04:47' AND '2017-02-20 06:04:47' AND handle_type = 2 GROUP BY room_id, from...【阅读全文】
1.对查询进行优化,应尽量避免全表扫描,首先应考虑在 where 及 order by 涉及的列上建立索引。2.应尽量避免在 where 子句中对字段进行 null 值判断,否则将导致引擎放弃使用索引而进行全表扫描,如:select id from t where num is null可以在num上设置默认值0,确保表中num列没有null值,然后这样查询:...【阅读全文】
-- 原表查询,字段较多SELECT SUM(`gift_num`*`gift_balance`) AS `balance`,`room_id`FROM `send_gift_history_info` WHERE `create_date` BETWEEN '2016-10-26 00:00:00' AND '2016-11-14 23:59:59'GROUP BY `room_id` ORDER BY balance DESC LIMIT 0,20;20 row(s) returnedExecution Time : 2 m...【阅读全文】
老鼠屎SELECT id, `user_in_room_time_id`, end_time INTO d2_user_in_room_time_history_id, d2_user_in_room_time_id, d_end_time FROM user_in_room_time_history WHERE user_id = NAME_CONST('v_user_id', 1962940) AND add_type = 1 ...【阅读全文】
老鼠屎!!!SELECT id, `user_in_room_time_id`, end_time INTO d2_user_in_room_time_history_id, d2_user_in_room_time_id, d_end_time FROM user_in_room_time_history WHERE user_id = NAME_CONST('v_user_id', 35560) AND add_type = 1&n...【阅读全文】