问题描述：
有什么可视化的，能够特别直观的分析SQL语句性能的工具？

select *  limit offset,amount;
select *  where id between offset and offset+amount;
select *  where id > offset limit amount;

以上三个SQL语句，哪个性能更佳呢？

解决方法：

可以用explain查看

mysql> explain select * from users  limit 1000,20;
+----+-------------+-------+------+---------------+------+---------+------+--------+-------+
| id | select_type | table | type | possible_keys | key  | key_len | ref  | rows   | Extra |
+----+-------------+-------+------+---------------+------+---------+------+--------+-------+
|  1 | SIMPLE      | users | ALL  | NULL          | NULL | NULL    | NULL | 169847 |       |
+----+-------------+-------+------+---------------+------+---------+------+--------+-------+
1 row in set (0.00 sec)
mysql> explain select * from users where uid>1000  limit 20;
+----+-------------+-------+-------+---------------+---------+---------+------+-------+-------------+
| id | select_type | table | type  | possible_keys | key     | key_len | ref  | rows  | Extra       |
+----+-------------+-------+-------+---------------+---------+---------+------+-------+-------------+
|  1 | SIMPLE      | users | range | PRIMARY       | PRIMARY | 4       | NULL | 84923 | Using where |
+----+-------------+-------+-------+---------------+---------+---------+------+-------+-------------+
1 row in set (0.00 sec)

mysql> explain select * from users where uid  between 1000 and 1020;
+----+-------------+-------+-------+---------------+---------+---------+------+------+-------------+
| id | select_type | table | type  | possible_keys | key     | key_len | ref  | rows | Extra       |
+----+-------------+-------+-------+---------------+---------+---------+------+------+-------------+
|  1 | SIMPLE      | users | range | PRIMARY       | PRIMARY | 4       | NULL |    1 | Using where |
+----+-------------+-------+-------+---------------+---------+---------+------+------+-------------+
1 row in set (0.00 sec)