Question

我有两个表tblReservation和tblBooking。 tblReservation有一个ID列和一个“事件名称”列。 tblBooking拥有自己的ID列，并且还具有Reservation ID列（外键），然后还有EventStart和EventEnd列。

基本上我正在做以下事情：

SELECT DISTINCT 
    B1.ReservationID,
    B1.EventStart,
    B1.EventEnd,
    tblReservation.EventName
FROM        
    tblBooking AS B1 
INNER JOIN
    tblReservation ON B1.ReservationID = tblReservation.ID
WHERE       
    B1.EventEnd = (SELECT MAX(B2.EventEnd)
                   FROM tblBooking AS B2
                   WHERE B2.ReservationID = B1.ReservationID)

我尝试了此子查询，每次预订仅提取一个预订ID。本质上我想要这些结果：

Reservation ID     EventStart    EventEnd     EventName
1                  1/1/18        1/2/18       Event 1
2                  1/2/18        1/3/18       Event 2 
3                  1/4/18        1/6/18       Event 3

相反，我得到了：

Reservation ID     EventStart    EventEnd     EventName
1                  1/1/18        1/1/18       Event 1
1                  1/2/18        1/2/18       Event 1
2                  1/2/18        1/2/18       Event 2
2                  1/3/18        1/3/18       Event 2

Answer 1

WITH X AS (
SELECT      
       B1.ReservationID
     , B1.EventStart
     , B1.EventEnd
     , tblReservation.EventName
     , ROW_NUMBER() OVER (PARTITION BY B1.ReservationID ORDER BY B1.[EventEnd] DESC) rn
FROM        tblBooking AS B1 
INNER JOIN  tblReservation ON B1.ReservationID = tblReservation.ID
)
SELECT 
       x.ReservationID
     , x.EventStart
     , x.EventEnd
     , x.EventName
FROM X 
WHERE x.rn = 1

Answer 2

select DISTINCT(B1.ReservationID), MIN(B1.EventStart) as EventStart, MAX(B1.EventEnd) as EventEnd, Res.EventName
from tblBooking B1
left join tblReservation Res on Res.ID = B1.ReservationID
GROUP BY B1.ReservationID, Res.EventName

SELECT DISTINCT问题，选择多个预订

2 个答案: