Generate Multiple rows from single row depending on date difference - tsql

Question

I want to generate multiple rows from 1 rows depending on dates difference in dtStart and dtEnd
-- This is demo table to show the issue
create table #temp(Id int,hTenant int , dtStart datetime,dtEnd datetime)
Insert into #temp values(1,8,'2013-01-08 00:00:00.000','2014-01-01 00:00:00.000')
And data should be returned by query as :-
**Id** **Tenant** **Month** **Year**
1 8 Aug 2013
1 8 Sep 2013
1 8 Oct 2013
1 8 Nov 2013
1 8 Dec 2013
1 8 Jan 2014
How i can achieve this
I have created one table valued function which returns month and year but not able to join it with the table to fetch id and tenant
Create FUNCTION vw_emg_common_GetYearMonthDiffList ( #startdt datetime,#enddt datetime )
RETURNS #Months TABLE
(
Months int,
Years int,
StartDate datetime,
EndDate datetime
)
AS
BEGIN
WHILE (#startdt< #enddt)
BEGIN
INSERT INTO #Months(Months,Years,StartDate,EndDate) VALUES (MONTH(#startdt),Year(#startdt),#startdt,#enddt)
SET #startdt = DATEADD(MONTH,1,#startdt)
end
INSERT #Months
Select Months,Years,StartDate,EndDate from #Months
RETURN
end
Function call :-
select * FROM vw_emg_common_GetYearMonthDiffList('2013-01-01 00:00:00.000','2013-12-01 00:00:00.000' )

Answer 1

Try this method using Cross Join and CTE. You may need to create a function (or slightly modify). Fiddle demo is here
DECLARE #sd DATE = '20130801', #ed DATE = '20140101',
#id INT = 1, #hTenant INT = 8
;WITH CTE AS
(
SELECT DATEDIFF(MONTH, #sd, #ed) Months
)
SELECT DISTINCT #id Id, #hTenant Tenant,
DATENAME(MONTH, DATEADD(MONTH, number, #sd)) [Month],
YEAR(DATEADD(MONTH, number, #sd)) [Year]
FROM master..spt_values x
CROSS JOIN CTE
WHERE x.number BETWEEN 0 AND Months
Results
| ID | TENANT | MONTH | YEAR |
|----|--------|-----------|------|
| 1 | 8 | August | 2013 |
| 1 | 8 | September | 2013 |
| 1 | 8 | October | 2013 |
| 1 | 8 | November | 2013 |
| 1 | 8 | December | 2013 |
| 1 | 8 | January | 2014 |

Answer 2

Hope this helps you.
DECLARE #TEMP TABLE(ID INT,TENANT INT , DTSTART DATETIME,DTEND DATETIME)
INSERT INTO #TEMP VALUES(1,8,'2013-01-08 00:00:00.000','2014-01-01 00:00:00.000')
--You can create a function with the given logic
--It receives STARTDATE and ENDDATE
DECLARE #STARTDATE DATETIME = (SELECT DTSTART FROM #TEMP),
#ENDDATE DATETIME = (SELECT DTEND FROM #TEMP)
DECLARE #S INT = CAST(#STARTDATE AS INT)
DECLARE #E INT = CAST(#ENDDATE AS INT)
DECLARE #TAB TABLE (ID INT, DT DATETIME)
WHILE #S <= #E
BEGIN
INSERT INTO #TAB VALUES (#S,CAST(#S AS DATETIME))
SET #S = #S + 1
END
SELECT TEMP.ID,TEMP.TENANT,[Mname] MONTH,[Y] YEAR FROM (
SELECT DATEPART(YEAR,DT) [Y],DATEPART(MONTH,DT) [Mnum],DATENAME(MONTH,DT) [Mname] FROM #TAB
GROUP BY DATEPART(YEAR,DT),DATEPART(MONTH,DT),DATENAME(MONTH,DT)) LU,#TEMP TEMP
ORDER BY [Y],[Mnum]
Result: