Question

我正在开发一个在线酒店管理系统项目，该数据库位于mssql中，其表名为BookingDetails，其中列名称为BookingId，BookingFrom和RoomNo。我需要找出一年内最多天数预订的RoomNo。我发现预订的客房预订了多少天; 像

select
    RoomNo
    BookingId,
    BookingUpto-BookingFrom

from 
    BookingDetails;

提供结果预订不同房间的天数，现在我的问题是如何使用所施加的数据i，e具有最小值，最大值或计数功能的天数。 Plz的帮助。谢谢。

表名BookingDetails

BookingID  BookingFrom               BookingUpto             RoomNo
Id
111        12/22/2013 12:00:00 AM    12/25/2013 12:00:00 AM  101
222        12/23/2013 12:00:00 AM    12/25/2013 12:00:00 AM  210
333        12/24/2013 12:00:00 AM    12/26/2013 12:00:00 AM  305
444        1/4/2014 12:00:00 AM      1/6/2014 12:00:00 AM    101
555        12/28/2013 12:00:00 AM    1/10/2014 12:00:00 AM   305
666        12/29/2013 12:00:00 AM    1/2/2014 12:00:00 AM    210
777        1/20/2014 12:00:00 AM     1/28/2014 12:00:00 AM   305
888        1/29/2014 12:00:00 AM     1/31/2014 12:00:00 AM   101
NULL       NULL                      NULL                    NULL

Answer 1

以下列出了每年预订每间客房的天数：

select RoomNo, sum(datediff(day, BookingFrom, BookingUpto)) as daysbooked
from BookingDetails
group by RoomNo;

您可以通过对此列表进行排序来找到预订时间最多的房间：

select RoomNo, sum(datediff(day, BookingFrom, BookingUpto)) as daysbooked
from BookingDetails
group by RoomNo
order by daysbooked desc;

Answer 2

尝试使用子查询，这将返回特定房间号的最大天数

select t.RoomNo, max(t.days)  from (
select RoomNo, BookingId, BookingUpto-BookingFrom days From BookingDetails) t
group by t.RoomNo

Answer 3

这对我有用： -

SELECT SUM(DateDiff * TotalCount) NumberOfDays,
       RoomNo
FROM   (SELECT SUM(DATEDIFF(day, BookingFrom, BookingUpTo)) DateDiff,
               RoomNo,
               count(1) TotalCount
        FROM   BookingDetails
        GROUP  BY BookingFrom,BookingUpTo,RoomNo) t
GROUP  BY RoomNo
ORDER  BY RoomNo

Answer 4

这应该得到你想要的。该小组每年和每个房间。由此我计算每次预订天数的总和（）。因此，如果有人从1月1日到1月4日预订，那应该是3晚预订（4日退房）。然后另一个人从1月4日到1月5日（一晚）预订房间。预订总共4晚。每个预订都会计算IT的住宿时间并将其加起来。

SELECT
      YEAR( BookingUpTo ) as Yr,
      roomNo,
      SUM( datediff( day, BookingUpTo, BookingFrom )) as totalBookedDays
  from 
     BookingDetails
  group by
     YEAR( BookingUpTo ),
     roomNo
  order by
     totalBookedDays DESC

找出一年中预订的最大天数

4 个答案: