mysql怎样添加字段?
发布时间:08/01 来源:未知 浏览:
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mysql怎样添加字段?
mysql添加两个字段:
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)
mysql添加一个字段:
alter table user add COLUMN new1 VARCHAR(20) DEFAULT NULL; //添加一个字段,默许为空 alter table user add COLUMN new2 VARCHAR(20) NOT NULL; //添加一个字段,默许不克不及为空
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