联合两个表并重命名表特定列

Question

我把表结合起来：

PkID | HouseFk | house_extra_id | Price | discount_id
1    | 5       | 6              | 1205  | 0

PkID | HouseFk | PacketFk | Price | discount_id
1    | 6       | 7        | 500   | 0

像这样使用union all：

select  pkid,housefk,house_extra_id,price,discount_id,null as packetfk
from T1

union all

select pkid,housefk,null as house_extra_id,price,discount_id,packetfk
from t2

结果是：

PkID | HouseFk | house_extra_id | Price | discount_id | PacketFk
1    | 5       | 6              | 1205  | 0           | NULL
1    | 6       | NULL           | 500   | 0           | 7

但是，如果我需要两个单独的“价格”列，具体取决于它与哪个表合并？所以最后我的表看起来像：

PkID | HouseFk | house_extra_id | t1_Price | t2_Price | discount_id | PacketFk
1    | 5       | 6              | 1205     | NULL     | 0           | NULL
1    | 6       | NULL           | NULL     | 500      | 0           | 7

Answer 1

您可以使用更多列，例如：

select  pkid, housefk, house_extra_id, 
        price AS t1_Price, NULL AS t2_Price,
        discount_id, null as packetfk
from T1

union all

select pkid, housefk, null as house_extra_id,
       NULL AS t1_Price, price AS t2_Price,
       discount_id, packetfk
from t2