如何合并两个表并在MySQL中添加带有记录的新列？
让我们首先创建一个表-
mysql> create table DemoTable1 -> ( -> 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 DemoTable1(Name) values('Chris');
mysql> insert into DemoTable1(Name) values('Robert');使用select语句显示表中的所有记录-
mysql> select *from DemoTable1;
输出结果
+----+--------+ | Id | Name | +----+--------+ | 1 | Chris | | 2 | Robert | +----+--------+ 2 rows in set (0.00 sec)
以下是创建第二个表的查询-
mysql> create table DemoTable2 -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Name varchar(100) -> );
使用插入命令在第二张表中插入一些记录-
mysql> insert into DemoTable2(Name) values('David');
mysql> insert into DemoTable2(Name) values('Bob');使用select语句显示第二个表中的所有记录-
mysql> select *from DemoTable2;
输出结果
+----+-------+ | Id | Name | +----+-------+ | 1 | David | | 2 | Bob | +----+-------+ 2 rows in set (0.00 sec)
以下是向两个表的联合添加新列的查询-
mysql> select Id,Name, 27 AS Age from DemoTable1 -> union -> select Id,name,20 AS Age from DemoTable2;
输出结果
+----+--------+-----+ | Id | Name | Age | +----+--------+-----+ | 1 | Chris | 27 | | 2 | Robert | 27 | | 1 | David | 20 | | 2 | Bob | 20 | +----+--------+-----+ 4 rows in set (0.00 sec)