Hotel Booking Rates SQL Problem

Question

Hi I\'ve been trying to get my own system for checking rooms rates going after reading other questions here on StackOverflow.

My query works fine and produces corre

Answer 1

Between 2011-04-16 16:00 and 2011-04-15 00:00 there is one day and 16 hours, therefore your DATEDIFF(...)+1 is returning (correctly) 1+1 days.

The issue here is the mismatch between the time when the guest arrives/leaves (around noon) and the time when the rate changes (at midnight).

You have to check your requirements, but probably you could ignore the last partial day and have the guest "leave" at 2011-04-15 23:59:59 for rate calculation purposes. In the same way, have the guest "arrive" at 2011-04-14 00:00:00. The extra hours in the first day will compensate the missing hours in the last day.

Answer 2

Thanks for your answers, Martin your produced 2 rows but no days...Emilio your answer got me thinking about how I had set up the rates. I changed the rate table to date format instead of datetime and made the rate_end_date the same day as the next rate_start_date.

0   66  2011-01-01  2011-04-15
1   70  2011-04-15  2011-06-01
2   80  2011-06-01  2011-07-01
3   100 2011-07-01  2011-09-01
4   80  2011-09-01  2011-10-01
5   70  2011-10-01  2011-11-01
6   45  2011-11-01  2012-01-01

then dropped the +1 and

SELECT rates.rate_id, rate_start_date, rate_end_date, rate_price, 
(DATEDIFF( IF (rate_end_date > '2011-04-16' , '2011-04-16', rate_end_date), 
IF ( rate_start_date < '2011-04-14' , '2011-04-14' , rate_start_date )) ) 
AS days FROM rates WHERE rate_start_date <= '2011-04-16' 
AND rate_end_date > '2011-04-14' 
ORDER BY rate_price ASC

produced

rate_id   rate_start_date   rate_end_date   rate  days    
    0   2011-01-01  2011-04-15  66  1
    1   2011-04-15  2011-06-01  70  1

and a query with no overlapping rates from the 1st to the 8th of April:

SELECT rates.rate_id, rate_start_date, rate_end_date, rate_price, 
(DATEDIFF( IF (rate_end_date > '2011-04-08' , '2011-04-08', rate_end_date), 
IF ( rate_start_date < '2011-04-01' , '2011-04-01' , rate_start_date )) ) 
AS days FROM rates WHERE rate_start_date <= '2011-04-08' 
AND rate_end_date > '2011-04-01' 
ORDER BY rate_price ASC

produces:

rate_id   rate_start_date    rate_end_date   rate  days
    0     2011-01-01       2011-04-15     66    7

thanks agiain for your help!

Answer 3

If I understand your algorithm correctly, you want to include first day even partially, so I would suggest you to use instead of + 1 for each rate do this only for the first one.

Try to use this (MSSQL):

+ CASE WHEN rate_start_date <= '2011-04-14 12:00:00' THEN 1 ELSE 0 end

or (MYSQL):

+ IF (rate_start_date <= '2011-04-14 12:00:00', 1 ,0)