Question

I have a table

tbl_charge

id hotel_id start_date  end_date    charge_per_day ( in $)  
1   6       2012-02-15  2010-02-15      20  
2   6       2012-02-16  2010-02-18      30  
4   6       2012-02-20  2010-02-25      50  

Note: if any date is not in the table then we set 25$ for each days (i.e. default charge)

now if someone wants to book a hotel from 2012-02-15 to 2012-02-22 , then I want to calculate the total charges for dates

Date   : 15+16+17+18+19+20+21+22
Charge : 20+30+30+30+25+50+50+50 = 285$

what i have done so far:

this query returns all rows successfully

SELECT * FROM `tbl_charge` WHERE 
start_date BETWEEN '2012-02-15' AND '2012-02-22' OR
end_date BETWEEN '2012-02-15' AND '2012-02-22' OR
( start_date <'2012-02-15' AND end_date > '2012-02-22')
HAVING property_id=6 

it returns all necessary rows but how do I sum the charges??

• is ther any way to count days between given date range like last row is 20 -25 but i want only upto 22 then it return 3 days and we multiply charges by 3
• is it good to create procedure for this or use simple query

Answer 1

I think this will do the trick:

select sum(DayDifference * charge_per_day) + 
        (RealDayDifference - sum(DayDifference)) * 25 as TotalPerPeriod
from (
  select charge_per_day, datediff(
      least(end_date, '2012-02-22'),
      greatest(start_date, '2012-02-15')) + 1 as DayDifference,
      datediff('2012-02-22', '2012-02-15') + 1 as RealDayDifference
  from t1
  where
    ((start_date between '2012-02-15' and '2012-02-22') or
    (end_date between '2012-02-15' and '2012-02-22') or
    (start_date < '2012-02-15' and end_date > '2012-02-22'))
    and hotel_id=6
) S1