从两个表中选择时添加一个额外的列

Question

我和我有两张桌子，网络和邮件。目前我正在使用此查询从两个表中获取数据。

PreparedStatement ps = con.prepareStatement("(select * from web where name='abc') union (select * from mail where name='abc')");
ResultSet rs = ps.executeQuery();
while(rs.next()){      
bw.write(rs3.getString("name")+"~"+rs3.getString("age")+"~"+rs3.getString("profession");
bw.newLine();
}

输出是这样的。

+------+------+------------+
| name | age  | profession |
+------+------+------------+
| abc  |   20 | doctor     |
| abc  |   20 | engineer   |
+------+------+------------+

在文件中就像这样

abc~20~doctor
abc~20~engineer

但是如何在结果集中添加额外的列，这将为我提供此格式的数据

abc~20~doctor~web
abc~20~engineer~mail

Answer 1

try this 

select * , 'web' as tablename from web where name='abc' union
select * ,'mail' as table namefrom mail where name='abc'

Answer 2

试试这个

PreparedStatement ps = con.prepareStatement("(select name,age,profession ,'web' AS ExtraColumnfrom from web where name='abc') union (select name,age,profession ,'mail' AS ExtraColumnfrom mail where name='abc')");
ResultSet rs = ps.executeQuery();
while(rs.next()){      
bw.write(rs3.getString("name")+"~"+rs3.getString("age")+"~"+rs3.getString("profession")+"~"+rs3.getString("ExtraColumnfrom ");
bw.newLine();
}

Answer 3

select * , 'web' as source from web where name='abc' union
select *, 'mail' as source from mail where name ='abc'