数据字段操作

修改数据表字段类型

alter table user modify name varchar(20);

增加表字段(first/after)

alter table user add column sex int(2);

+-------+-------------+------+-----+---------+-------+
| Field | Type        | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| name  | varchar(20) | YES  |     | NULL    |       |
| phone | int         | YES  |     | NULL    |       |
| sex   | int         | YES  |     | NULL    |       |
+-------+-------------+------+-----+---------+-------+

在指定位置插入新字段(first/after)

alter table user add column password varchar(16) AFTER phone;

+----------+-------------+------+-----+---------+-------+
| Field    | Type        | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| name     | varchar(20) | YES  |     | NULL    |       |
| phone    | int         | YES  |     | NULL    |       |
| password | varchar(16) | YES  |     | NULL    |       |
| sex      | int         | YES  |     | NULL    |       |
+----------+-------------+------+-----+---------+-------+

删除表字段

alter table user drop column sex;

表字段改名(first/after)

alter table user change name username varchar(8);

+----------+-------------+------+-----+---------+-------+
| Field    | Type        | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| username | varchar(8)  | YES  |     | NULL    |       |
| phone    | int         | YES  |     | NULL    |       |
| password | varchar(16) | YES  |     | NULL    |       |
+----------+-------------+------+-----+---------+-------+