Get Time Slots between two dates in SQL Server - sql

Question

I am not good in dealing with dates in SQL. I want to get full and partial day time slots between two dates in SQL Server.
Bit more explained.
For example, my date range is below:
StartDate - '2017-07-26 10:30:00'
End Date - '2017-07-29 16:45:00'
I want to populate time slots like below.
slot 1 - 2017-07-26 10:30:00 - 2017-07-26 23:59:00
slot 2 - 2017-07-27 00:00:00 - 2017-07-27 23:59:00
slot 3 - 2017-07-28 00:00:00 - 2017-07-28 23:59:00
slot 4 - 2017-07-29 00:00:00 - 2017-07-29 16:45:00
26 th and 29 th are not full days.
Does anyone have an idea how to achieve this in SQL Server? I can use a loop and do this but there will be performance issues. I tried with a recursive CTE, but it didn't work.
Thanks in advance. :)

Answer 1

This can be easily done using calendar table.. Here is one approach using Recursive CTE which generates dates on the fly
DECLARE #StartDate DATETIME = '2017-07-26 10:30:00',
#EndDate DATETIME = '2017-07-29 16:45:00';
WITH cte
AS (SELECT #StartDate st
UNION ALL
SELECT Cast(Cast(Dateadd(dd, 1, st) AS DATE) AS DATETIME)
FROM cte
WHERE st < CAST(#enddate AS DATE))
SELECT st,
CASE
WHEN #EndDate < Dateadd(mi, -1, Cast(Dateadd(dd, 1, Cast(st AS DATE)) AS DATETIME)) THEN #EndDate
ELSE Dateadd(mi, -1, Cast(Dateadd(dd, 1, Cast(st AS DATE)) AS DATETIME) )
END AS ed
FROM cte
I suggest you to create a physical calendar table to do this.
Rextester Demo

Answer 2

You can use CTE as below:
Declare #StartDate datetime = '2017-07-26 10:30:00'
Declare #EndDate datetime = '2017-07-29 16:45:00'
;with Cte_dates as (
Select dateadd(dd,1,Datediff(dd,0,#StartDate)) as StDate
Union All
Select DATEADD(dd,1, StDate) from Cte_dates where StDate < DAteADd(dd, -2, #endDate)
)
Select #StartDate as StartSlot, DateAdd(mi, -1,dateadd(dd,1,Datediff(dd,0,#StartDate))) as EndSlot
Union all
Select StDate as StartSlot,Dateadd(mi,-1, dateadd(dd,1,stDate)) EndSlot from Cte_dates --Generates from CTE for in between slots
Union all
Select Dateadd(dd,0,Datediff(dd,0,#EndDate)) as StartSlot, #EndDate as EndSlot
Output as below:
+-------------------------+-------------------------+
| StartSlot | EndSlot |
+-------------------------+-------------------------+
| 2017-07-26 10:30:00.000 | 2017-07-26 23:59:00.000 |
| 2017-07-27 00:00:00.000 | 2017-07-27 23:59:00.000 |
| 2017-07-28 00:00:00.000 | 2017-07-28 23:59:00.000 |
| 2017-07-29 00:00:00.000 | 2017-07-29 16:45:00.000 |
+-------------------------+-------------------------+