LEFT JOIN不工作

Question

我將嘗試開始日期和結束日期，以顯示我的酒店的免費客房

當我使用這個代碼只顯示我的房間至極出現在保留意見，但是它不要讓我看到從未預訂過的房間。

SELECT room.RoomID,room.Room_Type_ID,room.Room_number,room.NumberofSpots, 
res.Data_Check_in,res.Data_Check_out FROM  

     dbo.Reservation res JOIN dbo.Room room ON room.RoomID=res.Room_ID 
     WHERE NOT(res.Data_Check_in<=@p_StartData AND res.Data_Check_out>=@p_EndData) 

當我使用此代碼它的展示我所有的房間甚至那些保留：

SELECT DISTINCT r.* 
FROM dbo.Room r LEFT JOIN dbo.Reservation res ON r.RoomID=res.Room_ID 
AND NOT(res.Data_Check_in<='2012-05-07' AND res.Data_Check_out>='2012-06-13') 
AND res.Cancel=0 

我應該怎麼修改讓所有沒有這些房間留作選定的日期？

Answer 1

請原諒在變量名和列名的使用日期，而不是數據。

declare @p_StartDate as Date = '2012-05-07' 
declare @p_EndDate as Date = '2012-06-13' 

declare @Room as Table (Room_ID Int Identity, Room_number VarChar(5)) 
insert into @Room (Room_number) values 
    ('101'), ('102'), ('103'), ('104'), ('105'), 
    ('201'), ('202'), ('203'), ('204'), ('205') 

declare @Reservation as Table (ReservationID Int Identity, Room_ID Int, Date_Check_in Date, Date_Check_out Date, Cancel Bit) 
insert into @Reservation (Room_ID, Date_Check_in, Date_Check_out, Cancel) values 
    (3, '2012-05-01', '2012-05-06', 0), -- Before. 
    (3, '2012-06-14', '2012-07-01', 0), -- After. 
    (4, '2012-05-07', '2012-06-13', 0), -- Matching. 
    (5, '2012-06-01', '2012-06-05', 0), -- Within. 
    (6, '2012-05-01', '2012-06-01', 0), -- Overlapping start. 
    (7, '2012-06-01', '2012-06-15', 0), -- Overlapping end. 
    (8, '2012-06-01', '2012-06-05', 1), -- Within, but cancelled. 
    (9, '2012-06-01', '2012-06-15', 1), -- Overlapping, but cancelled. 
    (10, '2012-01-01', '2012-12-31', 0) -- Containing. 

select room.Room_ID, room.Room_number 
    from @Room as room 
    where not exists (
    select 42 
     from @Reservation 
     where Room_ID = room.Room_ID and Cancel = 0 and 
     -- The date ranges overlap. 
     (((@p_StartDate <= Date_Check_in) and (Date_Check_in <= @p_EndDate) or 
     (@p_StartDate <= Date_Check_out) and (Date_Check_out <= @p_EndDate)) or 
     -- The desired range is contained in the reserved range. 
     ((Date_Check_in <= @p_StartDate) and (@p_EndDate <= Date_Check_out)))) 

Answer 2

如何

SELECT Dr.* FROM dbo.Room r LEFT JOIN dbo.Reservation res 
ON r.RoomID=res.Room_ID 
WHERE res.Room_ID IS NULL 

對於房間永遠保留。

左連接不會與房間保留但不是今天幫助。對於你想要的東西像

SELECT Room_ID FROM Reservation WHERE Data_Check_out<=? OR Data_Check_in>=? 
OR (Data_Check_out<=? AND Data_Check_in<=? AND Cancel=1) 

一些很好的意見。我們知道左邊的加入會給我們「從未用過的房間」。

如果沒有取消字段以下應該工作：

組@checkindate = '2012-05-15';

組@checkoutdate = '2012-05-17';從預訂

選擇ROOM_ID哪裏都不（ Data_Check_in和Data_Check_out OR Data_Check_in和Data_Check_out之間@checkoutdate之間@checkindate）

但取消使事情變得更難，因爲我們需要知道，所有的日子希望可用。這種感覺更像是在個別日子裏設定的操作。