如果存在多个日期间隔，如何找到最适合哪个日期间隔的给定日期

Question

i am having two table one is having check in checkout dates and other information about client and other table is having rates room type hotel id and dates from when to when rates are valid. now the problem is this if rate table has three start and end date and check in date lies in three of those date ranges it shows the three records while the requirement is it should choose nearest start date For example is

start date  end date   room rate  
2013-10-01  2014-03-31 2000
2013-11-01  2013-12-20 2500
2013-12-21  2013-12-31 3000

and check in date is 25-12-2013 it should show record with only date range 3 which best fits to it my sql query is below `

 select b.*, r.* from(select a.Enquiry_Id,a.Ckeck_In,a.check_Out,a.Place,a.Hotel_Name,a.Meal_Plan,a.Room_Type,a.Occupancy_Type,a.Extra_Bed,a.Room_QT,h.grade,
 h.addres, h.Hotel_ID, a.ChildWithBed,a.childAgeWithoutBed,
 a.Inclusion, a.No_Night from Accomodation a inner join hotel h on
 a.Hotel_Name = h.Hotel_Name where a.Enquiry_Id = '0128201408') b inner
 join  RoomType r on b.Hotel_ID = r.Hotel_ID where r.Name = b.Room_Type
 and b.Ckeck_In between r.StartSeason and r.EndSeason order by Ckeck_`In

Answer 1

Try smth like this:

with (
    select 
        a.Enquiry_Id,a.Ckeck_In,a.check_Out,a.Place,
        a.Hotel_Name,a.Meal_Plan,a.Room_Type,
        a.Occupancy_Type,a.Extra_Bed,a.Room_QT,h.grade,
        h.addres, h.Hotel_ID, a.ChildWithBed,a.childAgeWithoutBed,
        a.Inclusion, a.No_Night 
    from Accomodation a 
    join hotel h on
        a.Hotel_Name = h.Hotel_Name 
    where 
        a.Enquiry_Id = '0128201408'
) temp
select
    temp.*, r.*
from temp
join (
    select 
        r.Hotel_ID, temp.Enquiry_Id, min(datediff(day, r.StartSeason, temp.Check_In)) MinDateDiff
    from temp
    join RoomType r on 
        temp.Hotel_ID = r.Hotel_ID 
    where 
        r.Name = temp.Room_Type
        and temp.Ckeck_In between r.StartSeason and r.EndSeason
    group by
        r.Hotel_ID, temp.Enquiry_Id
) x on
    temp.Enquiry_Id = x.Enquiry_Id
    and temp.Hotel_ID = x.Hotel_ID
join RoomType r on 
    x.Hotel_ID = r.Hotel_ID 
where 
    r.Name = temp.Room_Type
    and temp.Ckeck_In between r.StartSeason and r.EndSeason
    and datediff(day, r.StartSeason, temp.Check_In) = x.MinDateDiff
order by
    temp.Check_In

I'm calculating min datediff between StartSeason and Check_In, put it in a subquery and then rely on this datediff to get only the nearest records. I could make mistakes in the subquery grouping and in the outmost join. Just check it and correct if needed.