MySQL查询语句执行过程及性能优化-查询过程及优化方法（JOIN/ORDER BY）(二)
实施1、2、3的优化方法后，EXPLAIN结果如下：
[plain] mysql> explain select user.Username, user_profile.nickname, user_profile.gender, user_profile.meet_receive from user_profile join users on users.Id = user_profile.user_id where user_profile.`display` = '1' order by user_profile.fl_no limit 50; +----+-------------+---------------+--------+---------------+---------+---------+---------------------------------+------+--------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+---------------+--------+---------------+---------+---------+---------------------------------+------+--------------------------+ | 1 | SIMPLE | user_profile1 | index | NULL | fl_no | 4 | NULL | 50 | Using where | | 1 | SIMPLE | users | eq_ref | PRIMARY | PRIMARY | 8 | slowquery.user_profile1.user_id | 1 | Using where | +----+-------------+---------------+--------+---------------+---------+---------+---------------------------------+------+--------------------------+ 2 rows in set (0.00 sec)
备注：编写简单的PHP应用，用siege测试，查询效率提高>3倍。