Split date range (timestamp) into equal parts by Month- SQL Server

datesplit

Experts,
Have a question regarding splitting a date range into equal parts by months including the time part

example – fromdate – 06/29/2020 09:00:00 and todate – 06/29/2021 09:00:00

Want to split this date range into twelve equal parts like below

06/29/2020 09:00:00 - 06/30/2020 12:59:59
07/01/2020 00:00:00 - 07/31/2020 12:59:59
.........
.......
06/01/2021 00:00:00 - 06/29/2021 09:00:00

I cant write recursive CTE as this is a sql synapse module I am running against..

With below query I am able to split the date part, but time part is not coming properly as above.. Please help me as this is a blocking my development

declare @FromTs DATETIME
declare @ToTs DATETIME
SET @FromTs = GetDate()
SET @ToTs = DATEADD(month, 12, @FromTs)

;WITH n(n) AS 
(
    SELECT ROW_NUMBER() OVER (ORDER BY [object_id])-1 FROM sys.all_columns
),
d(qi,qrt,qtt,n,f,t,md,bp,ep,rn) AS  
(
    SELECT 
    ,n.n, @FromTs, @ToTs, 
    DATEDIFF(MONTH, @FromTs, @ToTs),
    DATEADD(MONTH, n.n, DATEADD(DAY, 1-DAY( @FromTs),  @FromTs)),
    DATEADD(DAY, -1, DATEADD(MONTH, 1, DATEADD(MONTH, n.n, 
    DATEADD(DAY, 1-DAY( @FromTs),  @FromTs))))
    FROM n INNER JOIN <datetbl> AS d 
    ON @ToTs >= DATEADD(MONTH, n.n-1, @FromTs)
)
SELECT qi,qrt,qtt,
new_from_date = CASE n WHEN 0  THEN f ELSE bp END,
new_to_date   = CASE n WHEN md THEN t ELSE ep END,rn
FROM d WHERE md >= n

Best Answer

WITH 
-- Range borders
src_data AS (SELECT CAST('2020-06-29 09:00:00' AS DATETIME) AS fromdate, 
                    CAST('2021-06-29 09:00:00' AS DATETIME) AS todate),
-- numbers table
numbers AS (SELECT 0 num UNION SELECT 1 UNION SELECT 2 UNION SELECT 3
             UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7
             UNION SELECT 8 UNION SELECT 9 UNION SELECT 10 UNION SELECT 11)                         
-- The query
SELECT num + 1 id, 
       DATEADD(SECOND, num * DATEDIFF(SECOND, fromdate, todate) / 12, fromdate) fromdate,
       DATEADD(SECOND, (num + 1) * DATEDIFF(SECOND, fromdate, todate) / 12, fromdate) todate
FROM src_data, numbers
ORDER BY id;

fiddle

The range is divided to equal (in seconds) parts. You may alter the calculations granularity (for example, use HOURS instead of SECOND), parts lengths will be adjusted and rounded automatically.

You may replace numbers CTE with any other which gets/generates the integers list from 0 to parts_amount-1, and parametrize the divident used in a query (12, may be replaced with, for example, SELECT COUNT(num) FROM numbers).

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