如何从MySQL的枚举中删除值？
使用ALTER命令从MySQL的枚举中删除一个值。让我们首先创建一个表-
mysql> create table DemoTable
(
`Rank` ENUM('LOW','MEDIUM','HIGH')
);
Query OK, 0 rows affected (0.52 sec)让我们检查表的描述。
mysql> DESC DemoTable;
这将产生以下输出-
+-------+-----------------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-----------------------------+------+-----+---------+-------+
| Rank | enum('LOW','MEDIUM','HIGH') | YES | | NULL | |
+-------+-----------------------------+------+-----+---------+-------+
1 row in set (0.00 sec)以下是从MySQL枚举中删除值的查询。
mysql> alter table DemoTable change `Rank` `Rank` ENUM('LOW','HIGH');
Query OK, 0 rows affected (1.19 sec)
Records: 0 Duplicates: 0 Warnings: 0现在让我们再次检查表的描述-
mysql> DESC DemoTable;
这将产生以下输出-
+-------+--------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+--------------------+------+-----+---------+-------+
| Rank | enum('LOW','HIGH') | YES | | NULL | |
+-------+--------------------+------+-----+---------+-------+
1 row in set (0.00 sec)