让我们首先创建一个表-
mysql> create table DemoTable( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Name varchar(100) );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable(Name) values('John'); mysql> insert into DemoTable(Name) values('Bob'); mysql> insert into DemoTable(Name) values('Adam');
使用select语句显示表中的所有记录-
mysql> select *from DemoTable;
这将产生以下输出-
+----+------+ | Id | Name | +----+------+ | 1 | John | | 2 | Bob | | 3 | Adam | +----+------+ 3 rows in set (0.00 sec)
这是添加列的查询-
mysql> alter table DemoTable add column Gender ENUM('MALE','FEMALE'); Records :0 Duplicates : 0 Warnings : 0
以下是将数据插入到现有表的新列中的查询-
mysql> update DemoTable set Gender='FEMALE' where Id=2; Rows matched − 1 Changed − 1 Warnings − 0
让我们再次检查表记录-
mysql> select *from DemoTable;
这将产生以下输出-
+----+------+--------+ | Id | Name | Gender | +----+------+--------+ | 1 | John | NULL | | 2 | Bob | FEMALE | | 3 | Adam | NULL | +----+------+--------+ 3 rows in set (0.00 sec)