MySQL常用辅助语句

查看索引：

mysql> show index from user_info;
+-----------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table     | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-----------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| user_info |          0 | PRIMARY  |            1 | id          | A         |           6 | NULL     | NULL   |      | BTREE      |         |               |
+-----------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
1 row in set

查看键：

mysql> show keys from user_info;
+-----------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table     | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-----------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| user_info |          0 | PRIMARY  |            1 | id          | A         |           6 | NULL     | NULL   |      | BTREE      |         |               |
+-----------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
1 row in set

查看语句的耗时：

mysql> set profiling = 1;
Query OK, 0 rows affected

mysql> select * from word_list where word like 'b%';
+-----------+-----------------------------------------------+------+
| word      | paraphrase                                    | sign |
+-----------+-----------------------------------------------+------+
| backward  | a. 向后的; ad. 向后                           | F    |
| bar       | vt. 1.阻止，不许 2.阻碍，阻塞 n. 酒吧，吧台   | F    |
| being     | n. 1.生物，人 2.存在                          | F    |
| billboard | n. 布告板,揭示栏,广告牌                       | F    |
| billion   | num.&n. 十亿                                  | F    |
| butterfly | n. 蝴蝶                                       | F    |
+-----------+-----------------------------------------------+------+
6 rows in set

mysql> select * from word_list where word like 'c%';
+----------------+----------------------------------+------+
| word           | paraphrase                       | sign |
+----------------+----------------------------------+------+
| capital-driven | a. 追求更多资本的                | F    |
| cartoon        | n. 动画片; vt. 为...画漫画       | T    |
| chart          | n. 图，图表 vt. 制图表           | F    |
| cholesterol    | n. 胆固醇                        | F    |
| circuit        | n. 电路,一圈,巡回                | F    |
| civil          | a. 国内的,公民的,国民的          | F    |
| civilization   | n. 文明,文化                     | F    |
| classical      | a. 古典的                        | F    |
| colonial       | a. 殖民地的; n. 殖民地居民       | F    |
| colonialism    | n. 殖民主义                      | F    |
| commercial     | a. 商业的; n. 商业广告           | F    |
| comparison     | n. 比较                          | F    |
| competition    | n. 比赛,竞争                     | F    |
| competitive    | a. 竞争的,比赛的                 | F    |
| compute        | 计算                             | F    |
| conference     | n. 会议                          | F    |
| confine        | v. 限制,闭居; [计算机] 限制      | F    |
| congress       | n. 代表大会,国会,议会；男女性交  | F    |
| consequence    | ad. 因而,所以; n. 结果,后果      | F    |
| constant       | a. 经常的,不变的; n. 常数,恒量   | F    |
| constantly     | ad. 不断地,经常地                | F    |
| construct      | v. 构造,建造,想出                | F    |
| constructive   | a. 建设性的,构造上的,作图的      | F    |
| consumeristic  | adj. 消费主义的                  | F    |
| consumption    | n. 消费                          | F    |
| contribution   | n. 贡献                          | F    |
| cooperate      | vi. 合作，协作，配合             | F    |
| corporation    | n. 公司                          | F    |
| cycle          | n. 循环,周期; v. 骑自行车        | F    |
+----------------+----------------------------------+------+
29 rows in set

mysql> show profiles;
+----------+------------+----------------------------------------------+
| Query_ID | Duration   | Query                                        |
+----------+------------+----------------------------------------------+
|        1 |    0.00065 | select * from word_list where word like 'b%' |
|        2 | 0.00047325 | select * from word_list where word like 'c%' |
+----------+------------+----------------------------------------------+
2 rows in set

查看执行语句的详细情况：

mysql> explain select * from word_list where word like 'c%';
+----+-------------+-----------+-------+---------------+---------+---------+------+------+-------------+
| id | select_type | table     | type  | possible_keys | key     | key_len | ref  | rows | Extra       |
+----+-------------+-----------+-------+---------------+---------+---------+------+------+-------------+
|  1 | SIMPLE      | word_list | range | PRIMARY       | PRIMARY | 92      | NULL |   29 | Using where |
+----+-------------+-----------+-------+---------------+---------+---------+------+------+-------------+
1 row in set

后待补充