如何使用子查询将这些查询合并为 1

Question

 Select * from HotelPerson 
 Where RoomID IN (select ID from HotelRoom Where BookingID = 36 )

 Select * from HotelCancelationPolicy 
 Where RoomID IN (select ID from HotelRoom Where BookingID = 36 )

如何将这两个查询合并为 1 个查询？

Answer 1

使用UNION获取不同的元素或UNION ALL获取两个表中的所有行

 Select * from HotelPerson 
 Where RoomID IN (select ID from HotelRoom Where BookingID = 36 )
 UNION ALL
 Select * from HotelCancelationPolicy 
 Where RoomID IN (select ID from HotelRoom Where BookingID = 36 )

Answer 2

我猜你想加入两个表：

    select * 
      from HotelPerson hp
inner join HotelCancelationPolicy hcp
        on hp.RoomId = hcp.RoomId
     where hp.RoomID IN (select ID 
                           from HotelRoom 
                          where BookingID = 36 )

Answer 3

这会将两个 table 的所有列合并为一个 table。

SELECT * 
FROM HotelPerson A, HotelCancelationPolicy B
WHERE A.RoomID = B.RoomID
AND A.RoomID IN (SELECT ID FROM HotelRoom WHERE BookingID = 36)

如何使用子查询将这些查询合并为 1

How to merge these queries into 1 using subquery

sql

subquery

correlated-subquery