MySQL的show columns命令

show columns

显示表的列信息。完整语法如下：

SHOW [FULL] COLUMNS FROM tbl_name [FROM db_name] [like_or_where]

实例：使用 show columns 查看 city 表格的结构。如下：

mysql> show columns from city;
+-------------+----------+------+-----+---------+----------------+
| Field       | Type     | Null | Key | Default | Extra          |
+-------------+----------+------+-----+---------+----------------+
| ID          | int(11)  | NO   | PRI | NULL    | auto_increment |
| Name        | char(35) | NO   |     |         |                |
| CountryCode | char(3)  | NO   | MUL |         |                |
| District    | char(20) | NO   |     |         |                |
| Population  | int(11)  | NO   |     | 0       |                |
+-------------+----------+------+-----+---------+----------------+
5 rows in set (0.01 sec)

使用 show full 显示表格详细信息。如下：

mysql> show full columns from city;
+-------------+----------+-------------------+------+-----+---------+----------------+---------------------------------+---------+
| Field       | Type     | Collation         | Null | Key | Default | Extra          | Privileges                      | Comment |
+-------------+----------+-------------------+------+-----+---------+----------------+---------------------------------+---------+
| ID          | int(11)  | NULL              | NO   | PRI | NULL    | auto_increment | select,insert,update,references |         |
| Name        | char(35) | latin1_swedish_ci | NO   |     |         |                | select,insert,update,references |         |
| CountryCode | char(3)  | latin1_swedish_ci | NO   | MUL |         |                | select,insert,update,references |         |
| District    | char(20) | latin1_swedish_ci | NO   |     |         |                | select,insert,update,references |         |
| Population  | int(11)  | NULL              | NO   |     | 0       |                | select,insert,update,references |         |
+-------------+----------+-------------------+------+-----+---------+----------------+---------------------------------+---------+
5 rows in set (0.00 sec)

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使用 show columns from tableName from dbName 查看指定数据库下面指定表格的结构。如下：

mysql> show columns from city from world;
+-------------+----------+------+-----+---------+----------------+
| Field       | Type     | Null | Key | Default | Extra          |
+-------------+----------+------+-----+---------+----------------+
| ID          | int(11)  | NO   | PRI | NULL    | auto_increment |
| Name        | char(35) | NO   |     |         |                |
| CountryCode | char(3)  | NO   | MUL |         |                |
| District    | char(20) | NO   |     |         |                |
| Population  | int(11)  | NO   |     | 0       |                |
+-------------+----------+------+-----+---------+----------------+
5 rows in set (0.00 sec)