添加額外的列，同時從兩個表中選擇

Question

我有兩個表與我，網絡和郵件。目前我正在使用此查詢從兩個表中獲取數據。

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(); 
} 

輸出是這樣的。

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

，並在文件中的像這樣

abc~20~doctor 
abc~20~engineer 

，但我怎麼能在結果集中，這將給我的數據，這種格式

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

Answer 1

添加一個額外的列

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

Answer 2

try this 

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

Answer 3

試試這個

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(); 
}