注释：

以/**注释内容**/

mysql> /**列出所有的数据库**/ show databases;

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

| Database           |

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

| information_schema |

| db_springcloud     |

| mysql              |

| performance_schema |

| test               |

| wordpress          |

| xinyu              |

| xinyu2             |

| zabbix             |

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

9 rows in set (0.00 sec)

###注释是从‘#’字符到行尾

mysql> #这里是注释，到行尾都是注释，所以后面的命令不执行 showdatabases;

mysql> 

如果遇到很长的sql语句的话，在控制台为了阅读方便，我们可以使用\，使之继续输入；

mysql> show \

    -> databases;

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

| Database           |

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

| information_schema |

| db_springcloud     |

| mysql              |

| performance_schema |

| test               |

| wordpress          |

| xinyu              |

| xinyu2             |

| zabbix             |

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

9 rows in set (0.00 sec)

mysql>

也支持正则like查询

mysql> show databases like '%inyu%';

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

| Database (%inyu%) |

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

| xinyu             |

| xinyu2            |

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

2 rows in set (0.00 sec)

同理，show tables也支持，用from语法，可以少一步use 数据库

mysql> show tables from test;

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

| Tables_in_test |

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

| hbk            |

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

1 row in set (0.00 sec)

mysql> show tables from test like '%b%';


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


| Tables_in_test (%b%) |


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


| hbk                  |


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


1 row in set (0.00 sec)

查看表定义，可以使用show create table 表名 \G

\G只是显示的格式更好看而已，也可以使用describe语法

mysql> use test;

mysql> show create table hbk \G;

*************************** 1. row ***************************

       Table: hbk

Create Table: CREATE TABLE `hbk` (

  `id` int(11) NOT NULL AUTO_INCREMENT,

  `name` varchar(20) NOT NULL,

  PRIMARY KEY (`id`)

) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=latin1

1 row in set (0.00 sec)

ERROR:


No query specified

mysql> describe hbk;


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


| Field | Type        | Null | Key | Default | Extra          |


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


| id    | int(11)     | NO   | PRI | NULL    | auto_increment |


| name  | varchar(20) | NO   |     | NULL    |                |


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


2 rows in set (0.00 sec)

mysql> desc hbk;


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


| Field | Type        | Null | Key | Default | Extra          |


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


| id    | int(11)     | NO   | PRI | NULL    | auto_increment |


| name  | varchar(20) | NO   |     | NULL    |                |


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


2 rows in set (0.01 sec)

知识点注意：

数据名的最大长度64字节

表名的最大长度64字节

列名的最大长度64字节

索引名的最大长度64字节

别名的最大长度255字节

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