mysql - 如何将列的类型从 varchar(30) 更改为 varchar(100)？

Question

我有一个这样描述的表:

mysql> describe easy_table;
+---------------------+--------------+------+-----+---------+----------------+
| Field               | Type         | Null | Key | Default | Extra          |
+---------------------+--------------+------+-----+---------+----------------+
| id                  | bigint(20)   | NO   | PRI | NULL    | auto_increment |
| version             | bigint(20)   | NO   |     | NULL    |                |
| account_id          | bigint(20)   | NO   | MUL | NULL    |                |
| city                | varchar(30)  | NO   |     | NULL    |                |
...
| name                | varchar(255) | YES  |     | NULL    |                |
| name_two            | varchar(255) | YES  |     | NULL    |                |
+---------------------+--------------+------+-----+---------+----------------+
13 rows in set (0.03 sec)

我试图让城市 varchar 变大到 varchar(100)，但这条线不起作用

alter table easy_table alter column city varchar(100);

这也行不通

alter table easy_table alter column city varchar(100) not null;

我收到这个错误:

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'varchar(100)' at line 1

Answer 1

alter table easy_table modify column city varchar(100) not null;