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.