Sql 如何使用子查询将这些查询合并为1

如何将这两个查询合并为一个查询？

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 )

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

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我猜你想把这两个表连接起来：

 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 )

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这将为您提供一个表中两个表中的所有列

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

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Argh，不要对

WHERE

子句使用隐式联接，请使用显式联接。这种语法已经过时了，我不打算投反对票，但这是一个巨大的（有缺陷的）假设，即它们的表结构是相同的；否则，联合将失败。我假设您希望两个查询的结果都在一行中？只需在

RoomID上进行内部连接

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