如何在MySql中更改列默认值

我正在使用MySql5.5.

I am using MySql5.5.

我有一个表media__gallery，我想将列default_format的默认值从'NO'更改为'YES'，但是当我编写查询并通过命令行运行时，没有任何更新.

I have a table media__gallery and I want change the default value of the column default_format from 'NO' to 'YES', but when I write the query and run through command line nothing is updated.

我的查询:

ALTER TABLE `media__gallery` CHANGE `default_format` `default_format` VARCHAR( 255 ) CHARACTER SET latin1 COLLATE latin1_bin NULL DEFAULT 'YES';

MySql表:

mysql> desc media__gallery;
+----------------+--------------+------+-----+---------+----------------+
| Field          | Type         | Null | Key | Default | Extra          |
+----------------+--------------+------+-----+---------+----------------+
| id             | int(11)      | NO   | PRI | NULL    | auto_increment |
| name           | varchar(255) | NO   |     | NULL    |                |
| context        | varchar(64)  | NO   |     | NULL    |                |
| default_format | varchar(255) | NO   |     | NULL    |                |
| enabled        | tinyint(1)   | NO   |     | NULL    |                |
| updated_at     | datetime     | NO   |     | NULL    |                |
| created_at     | datetime     | NO   |     | NULL    |                |
| category_id    | int(11)      | YES  | UNI | NULL    |                |
+----------------+--------------+------+-----+---------+----------------+

我在这里想念什么?