修改列的类型:

    修改语句也用于修改表中列的类型，就像之前的例子一样。以下的查询就是修改列的类型。

mysql> alter table student modify name varchar(40);
Query OK, 0 rows affected (0.05 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc student;
+---------+-------------+------+-----+---------+-------+
| Field   | Type        | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| studid  | int(10)     | YES  |     | NULL    |       |
| name    | varchar(40) | YES  |     | NULL    |       |
| marks   | int(10)     | YES  |     | NULL    |       |
| address | varchar(40) | YES  |     | NULL    |       |
| phone   | int(10)     | YES  |     | NULL    |       |
+---------+-------------+------+-----+---------+-------+
5 rows in set (0.00 sec)