是的,我们可以对ALTER语句使用ADD和CHANGE。让我们首先创建一个表-
mysql> create table DemoTable -> ( -> Name varchar(100), -> Age int -> );
现在检查表的描述。
mysql> desc DemoTable;
输出结果
这将产生以下输出-
+-------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+--------------+------+-----+---------+-------+ | Name | varchar(100) | YES | | NULL | | | Age | int(11) | YES | | NULL | | +-------+--------------+------+-----+---------+-------+ 2 rows in set (0.25 sec)
这是使用ALTER进行的查询,用于更新列名以及添加新列-
mysql> alter table DemoTable -> add column Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> add column CountryName varchar(100) after Age, -> change column Name FirstName varchar(200); Records: 0 Duplicates: 0 Warnings: 0
现在再次检查表的描述-
mysql> desc DemoTable;
输出结果
这将产生以下输出-
+-------------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-------------+--------------+------+-----+---------+----------------+ | FirstName | varchar(200) | YES | | NULL | | | Age | int(11) | YES | | NULL | | | CountryName | varchar(100) | YES | | NULL | | | Id | int(11) | NO | PRI | NULL | auto_increment | +-------------+--------------+------+-----+---------+----------------+ 4 rows in set (0.00 sec)