语法帮助!! SQL更改表更改列varchar(30) - > varcahar(100)

Question

我收到一个超级n00b错误,需要语法帮助.

我有一个描述如下的表格:

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更大到varchar(100),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;

我收到此错误:

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)

Answer 1

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