增加列:
alter table table_name add name varchar(100);
alter table table_name add name varchar(100) after id;
alter table table_name add name varchar(100) first;
修改列名:
alter table table_name change name name varchar(10);
#change可改名字与字段类型
mysql> alter table a change uid uid int;
Query OK, 0 rows affected (0.04 sec)
Records: 0 Duplicates: 0 Warnings: 0
alter table table_name modify name int;
#modify只改字段类型
mysql> desc a;
+-------+---------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+-------+
| namea | char(1) | YES | | NULL | |
| id | int(11) | YES | | NULL | |
| uid | int(11) | YES | | NULL | |
+-------+---------+------+-----+---------+-------+
3 rows in set (0.01 sec)
mysql>
mysql>
mysql> alter table a modify uid varchar(1);
Query OK, 0 rows affected (0.07 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc a;
+-------+------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+------------+------+-----+---------+-------+
| namea | char(1) | YES | | NULL | |
| id | int(11) | YES | | NULL | |
| uid | varchar(1) | YES | | NULL | |
+-------+------------+------+-----+---------+-------+
3 rows in set (0.01 sec)
mysql>
删除列:
alter table table_name drop column_name;
#手册
help modify;
