MySQL資料庫中增加和刪除欄位
阿新 • • 發佈：2019-02-12
mysql> create table id_name(id int,name varchar(20)); Query OK, 0 rows affected (0.13 sec) mysql> alter table id_name add age int,add address varchar(11); Query OK, 0 rows affected (0.13 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc id_name； +---------+-------------+------+-----+---------+-------+| Field | Type | Null | Key | Default | Extra | +---------+-------------+------+-----+---------+-------+ | id | int(11) | YES | | NULL | | | name | varchar(20) | YES | | NULL | | | age | int(11) | YES | | NULL | | | address | varchar(11) | YES | | NULL | | +---------+-------------+------+-----+---------+-------+ 4 rows in set (0.00 sec) 2.刪除兩個欄位 mysql> alter table id_name drop column age,drop column address; Query OK, 0 rows affected (0.14 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc id_name; +-------+-------------+------+-----+---------+-------+| Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+-------+ | id | int(11) | YES | | NULL | | | name | varchar(20) | YES | | NULL | | +-------+-------------+------+-----+---------+-------+ 2 rows in set (0.00 sec) 3.插入 mysql> insert into id_name values (1,'qustdjx'); Query OK, 1 row affected (0.00 sec) 4.查詢看一下 mysql> alter table id_name add age int,add address varchar(11); Query OK, 1 row affected (0.07 sec) Records: 1 Duplicates: 0 Warnings: 0 mysql> select * from id_name; +------+---------+------+---------+ | id | name | age | address | +------+---------+------+---------+ | 1 | qustdjx | NULL | NULL | +------+---------+------+---------+ 1 row in set (0.00 sec) 5.新增欄位並插入 mysql> insert into id_name values(2,'qust',14,'山東'); Query OK, 1 row affected (0.00 sec) mysql> select * from id_name; +------+---------+------+---------+ | id | name | age | address | +------+---------+------+---------+ | 1 | qustdjx | NULL | NULL | | 2 | qust | 14 | 山東 | +------+---------+------+---------+ 2 rows in set (0.00 sec)