mysql> explain SELECT * FROM vlc_caomei_state

    -> WHERE

    -> city = '太原市'

    -> AND region='山西省'

    -> order by region

    -> ;

+----+-------------+------------------+------+---------------+---------+---------+-------------+-------+-----------------------+

| id | select_type | table            | type | possible_keys | key     | key_len | ref         | rows  | Extra                 |

+----+-------------+------------------+------+---------------+---------+---------+-------------+-------+-----------------------+

|  1 | SIMPLE      | vlc_caomei_state | ref  | regions       | regions | 306     | const,const | 60900 | Using index condition |

+----+-------------+------------------+------+---------------+---------+---------+-------------+-------+-----------------------+

1 row in set (0.02 sec)



mysql> show index from vlc_caomei_state ;

+------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+-----------

----+

| Table            | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comm

ent |

+------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+-----------

----+

| vlc_caomei_state |          0 | PRIMARY  |            1 | id          | A         |     3918061 |     NULL | NULL   |      | BTREE      |         |

    |

| vlc_caomei_state |          1 | time     |            1 | time        | A         |     3918061 |     NULL | NULL   | YES  | BTREE      |         |

    |

| vlc_caomei_state |          1 | version  |            1 | version     | A         |          96 |     NULL | NULL   | YES  | BTREE      |         |

    |

| vlc_caomei_state |          1 | versions |            1 | version_1   | A         |        1342 |     NULL | NULL   | YES  | BTREE      |         |

    |

| vlc_caomei_state |          1 | versions |            2 | version_2   | A         |        1342 |     NULL | NULL   | YES  | BTREE      |         |

    |

| vlc_caomei_state |          1 | versions |            3 | version_3   | A         |        1342 |     NULL | NULL   | YES  | BTREE      |         |

    |

| vlc_caomei_state |          1 | versions |            4 | version_4   | A         |        4703 |     NULL | NULL   | YES  | BTREE      |         |

    |

| vlc_caomei_state |          1 | regions  |            1 | region      | A         |          78 |     NULL | NULL   | YES  | BTREE      |         |

    |

| vlc_caomei_state |          1 | regions  |            2 | city        | A         |         782 |     NULL | NULL   | YES  | BTREE      |         |

    |

+------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+-----------

----+

9 rows in set (0.00 sec)



mysql>

#用时：28s

SELECT * FROM vlc_caomei_state   

WHERE   

city = '济南市'     

order by region  



#用时：24s

SELECT * FROM vlc_caomei_state   

WHERE   

city = '济南市'   

AND   

region='山东省'   

order by region  

#用时：++++(太慢)

SELECT * FROM vlc_caomei_state   

WHERE   

city = '济南市'     

order by region  

limit 0,10;

#用时：0.1s

SELECT * FROM vlc_caomei_state   

WHERE   

city = '济南市'   

AND   

region='山东省'   

order by region  

limit 0,10;