How to get the records grouping dates for a span of 3 days in SQL?

Question

It\'s getting difficult to group and display records every 5 days.

Here is my data:

FLIGHT         


        

Answer 1

Here it is my proposed solution:

DECLARE @MinDate AS DATETIME = (SELECT MIN(flight_date) FROM flights);

WITH cte
AS
(
    SELECT
        flight_date, DATEDIFF(DAY, @MinDate, flight_date) AS NoDays,
        DATEDIFF(DAY, @MinDate, flight_date)/5 AS NoGroup,
        DPT
    FROM flights
)
SELECT  
    DATEADD(DAY, NoGroup*5, @MinDate) AS [Week Start],
    DATEADD(DAY, NoGroup*5+4, @MinDate) AS [Weed End],  
    SUM(DPT)
FROM cte
GROUP BY NoGroup;

The idea is to form groups of 5 days, then associate a record to a specific group based on division with 5. NoDays represents the days spent from MinDate to Flight_Date.

Answer 2

You can use this query. You need to specify the start date from which you want to count and the number of days in each period (which seems to be 5 in your case) but please adjust those numbers as needed.

declare @startdate date = '20131117'
declare @interval int = 5

select dateadd(dd, @interval * (o.number - 1), @startdate) WeekStart, 
    dateadd(dd, @interval * o.number - 1, @startdate) WeekEnd,
    sum(d.DPT) DPT
from yourtable d
inner join
    (select ROW_NUMBER() over (order by object_id) as number from sys.all_objects) as o
on d.FLIGHT_DATE >= dateadd(dd, @interval * (o.number - 1), @startdate)
and d.FLIGHT_DATE < dateadd(dd, @interval * o.number, @startdate)
group by o.number
order by dateadd(dd, @interval * (o.number - 1), @startdate)