SQL Server Function - CTE defined but not used - sql-server

Question

I am trying to create function in SQL Server that returns months between range of dates passed to function. Below is my current script -
CREATE FUNCTION [dbo].[fn_get_date_range] (
#startDate datetime,
#endDate datetime,
#frequency varchar(20)
)
RETURNS
#dateRanges TABLE
(
report_date datetime
)
AS
BEGIN
WITH DateRange (report_date) AS
(
SELECT row_number() OVER (ORDER BY object_id) FROM sys.all_objects)
SELECT DATEADD(s,-1,DATEADD(mm, DATEDIFF(m,0,#StartDate)+report_date,0)
) AS report_date
insert into #dateRanges (report_date)
Select report_date FROM DateRange
WHERE report_date <= DATEDIFF(month, #StartDate, #EndDate)+1
RETURN
END
But when I try to create these function, I get below error -
Common table expression defined but not used.
I have tried different approach but it doesn't work. Any pointers in right direction would be appreciated. Thank you.

Answer 1

Here is my TVF used for dynamic datetime ranges.
Similar to your approach, but I do have the DATEPART as a parameter as well as the increment.
Example - Month Increment 1:
Select * from [dbo].[tvf-Range-Date]('2016-01-01','2017-01-01','MM',1)
Returns
Example - Minute Increment 15:
Select * from [dbo].[tvf-Range-Date]('2017-01-01','2017-01-02','MI',15)
Returns
The UDF if Interested
CREATE FUNCTION [dbo].[tvf-Range-Date] (#R1 datetime,#R2 datetime,#Part varchar(10),#Incr int)
Returns Table
Return (
with cte0(M) As (Select 1+Case #Part When 'YY' then DateDiff(YY,#R1,#R2)/#Incr When 'QQ' then DateDiff(QQ,#R1,#R2)/#Incr When 'MM' then DateDiff(MM,#R1,#R2)/#Incr When 'WK' then DateDiff(WK,#R1,#R2)/#Incr When 'DD' then DateDiff(DD,#R1,#R2)/#Incr When 'HH' then DateDiff(HH,#R1,#R2)/#Incr When 'MI' then DateDiff(MI,#R1,#R2)/#Incr When 'SS' then DateDiff(SS,#R1,#R2)/#Incr End),
cte1(N) As (Select 1 From (Values(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) N(N)),
cte2(N) As (Select Top (Select M from cte0) Row_Number() over (Order By (Select NULL)) From cte1 a, cte1 b, cte1 c, cte1 d, cte1 e, cte1 f, cte1 g, cte1 h ),
cte3(N,D) As (Select 0,#R1 Union All Select N,Case #Part When 'YY' then DateAdd(YY, N*#Incr, #R1) When 'QQ' then DateAdd(QQ, N*#Incr, #R1) When 'MM' then DateAdd(MM, N*#Incr, #R1) When 'WK' then DateAdd(WK, N*#Incr, #R1) When 'DD' then DateAdd(DD, N*#Incr, #R1) When 'HH' then DateAdd(HH, N*#Incr, #R1) When 'MI' then DateAdd(MI, N*#Incr, #R1) When 'SS' then DateAdd(SS, N*#Incr, #R1) End From cte2 )
Select RetSeq = N+1
,RetVal = D
From cte3,cte0
Where D<=#R2
)
/*
Max 100 million observations -- Date Parts YY QQ MM WK DD HH MI SS
Syntax:
Select * from [dbo].[tvf-Range-Date]('2016-10-01','2020-10-01','YY',1)
Select * from [dbo].[tvf-Range-Date]('2016-01-01','2017-01-01','MM',1)
*/
EDIT - As Requested
CREATE FUNCTION [dbo].[tvf-Range-Date-Span] (#R1 datetime,#R2 datetime,#Part varchar(10),#Incr int)
Returns Table
Return (
with cte0(M) As (Select 1+Case #Part When 'YY' then DateDiff(YY,#R1,#R2)/#Incr When 'QQ' then DateDiff(QQ,#R1,#R2)/#Incr When 'MM' then DateDiff(MM,#R1,#R2)/#Incr When 'WK' then DateDiff(WK,#R1,#R2)/#Incr When 'DD' then DateDiff(DD,#R1,#R2)/#Incr When 'HH' then DateDiff(HH,#R1,#R2)/#Incr When 'MI' then DateDiff(MI,#R1,#R2)/#Incr When 'SS' then DateDiff(SS,#R1,#R2)/#Incr End),
cte1(N) As (Select 1 From (Values(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) N(N)),
cte2(N) As (Select Top (Select M from cte0) Row_Number() over (Order By (Select NULL)) From cte1 a,cte1 b,cte1 c,cte1 d,cte1 e,cte1 f,cte1 g,cte1 h ),
cte3(N,D) As (Select 0,#R1 Union All Select N,Case #Part When 'YY' then DateAdd(YY,N*#Incr,#R1) When 'QQ' then DateAdd(QQ,N*#Incr,#R1) When 'MM' then DateAdd(MM,N*#Incr,#R1) When 'WK' then DateAdd(WK,N*#Incr,#R1) When 'DD' then DateAdd(DD,N*#Incr,#R1) When 'HH' then DateAdd(HH,N*#Incr,#R1) When 'MI' then DateAdd(MI,N*#Incr,#R1) When 'SS' then DateAdd(SS,N*#Incr,#R1) End From cte2 )
Select RetSeq = N+1
,RetVal1 = D
,RetVal2 = LEAD(D,1,#R2) over (Order By D)
From cte3,cte0
Where N<cte0.M-1
)
--Max 100 million observations -- Date Parts YY QQ MM WK DD HH MI SS
--Select * from [dbo].[tvf-Range-Date-Span]('2016-10-01','2020-10-01','YY',1)
Returns something like this
Edit 2 - For 2008
;with cte as (
Select * from [dbo].[tvf-Range-Date]('2016-01-01','2017-01-01','MM',1)
)
Select DateR1 = A.RetVal
,DateR2 = B.NxtDate
From cte A
Cross Apply (Select NxtDate=min(RetVal) from cte where RetVal > A.RetVal ) B
Where B.NxtDate is not null
Returns

Answer 2

It is not allowed that CTE is not followed by SELECT statement, cite from MS:
•A CTE must be followed by a single SELECT statement. INSERT, UPDATE,
DELETE, and MERGE statements are not supported.
UPDATE
CREATE FUNCTION [dbo].[fn_get_date_range] (
#startDate datetime,
#endDate datetime,
#frequency varchar(20)
)
RETURNS
#dateRanges TABLE
(
report_date datetime
)
AS
BEGIN
WITH DateRange (report_date) AS
(
SELECT row_number() OVER (ORDER BY object_id) FROM sys.all_objects)
SELECT DATEADD(s,-1,DATEADD(mm, DATEDIFF(m,0,#StartDate)+report_date,0)
) AS report_date
Select * FROM DateRange
INTO #temp_table
WHERE report_date <= DATEDIFF(month, #StartDate, #EndDate)+1
insert into #dateRanges (report_date)
select * from #temp_table
drop table #temp_table
RETURN
END

Answer 3

This is a variant that's similar to John's function...
CREATE FUNCTION dbo.tfn_BuildDateRanges
(
#startDate DATETIME,
#endDate DATETIME,
#dateInterval VARCHAR(20),
#interval INT
)
RETURNS TABLE WITH SCHEMABINDING AS
RETURN
WITH
cte_n1 (n) AS (SELECT 1 FROM (VALUES (1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) n (n)),
cte_n2 (n) AS (SELECT 1 FROM cte_n1 a CROSS JOIN cte_n1 b),
cte_n3 (n) AS (SELECT 1 FROM cte_n2 a CROSS JOIN cte_n2 b),
cte_Calendar AS (
SELECT TOP ((CASE
WHEN #dateInterval IN ('year', 'yy', 'yyyy') THEN DATEDIFF(year, #startDate, #endDate)
WHEN #dateInterval IN ('quarter', 'qq', 'q') THEN DATEDIFF(quarter, #startDate, #endDate)
WHEN #dateInterval IN ('month', 'mm', 'm') THEN DATEDIFF(month, #startDate, #endDate)
WHEN #dateInterval IN ('week wk, ww') THEN DATEDIFF(week, #startDate, #endDate)
WHEN #dateInterval IN ('day', 'dd', 'd') THEN DATEDIFF(day, #startDate, #endDate)
WHEN #dateInterval IN ('hour', 'hh') THEN DATEDIFF(hour, #startDate, #endDate)
WHEN #dateInterval IN ('minute', 'mi', 'n') THEN DATEDIFF(minute, #startDate, #endDate)
WHEN #dateInterval IN ('second', 'ss', 's') THEN DATEDIFF(second, #startDate, #endDate)
END / #interval + 1))
BegOfRange = CASE
WHEN #dateInterval IN ('year', 'yy', 'yyyy') THEN DATEADD(year, (ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) -1) * #interval, #startDate)
WHEN #dateInterval IN ('quarter', 'qq', 'q') THEN DATEADD(quarter, (ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) -1) * #interval, #startDate)
WHEN #dateInterval IN ('month', 'mm', 'm') THEN DATEADD(month, (ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) -1) * #interval, #startDate)
WHEN #dateInterval IN ('week wk, ww') THEN DATEADD(week, (ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) -1) * #interval, #startDate)
WHEN #dateInterval IN ('day', 'dd', 'd') THEN DATEADD(day, (ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) -1) * #interval, #startDate)
WHEN #dateInterval IN ('hour', 'hh') THEN DATEADD(hour, (ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) -1) * #interval, #startDate)
WHEN #dateInterval IN ('minute', 'mi', 'n') THEN DATEADD(minute, (ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) -1) * #interval, #startDate)
WHEN #dateInterval IN ('second', 'ss', 's') THEN DATEADD(second, (ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) -1) * #interval, #startDate)
END,
EndOfRange = CASE
WHEN #dateInterval IN ('year', 'yy', 'yyyy') THEN DATEADD(year, (ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) ) * #interval, #startDate)
WHEN #dateInterval IN ('quarter', 'qq', 'q') THEN DATEADD(quarter, (ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) ) * #interval, #startDate)
WHEN #dateInterval IN ('month', 'mm', 'm') THEN DATEADD(month, (ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) ) * #interval, #startDate)
WHEN #dateInterval IN ('week wk, ww') THEN DATEADD(week, (ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) ) * #interval, #startDate)
WHEN #dateInterval IN ('day', 'dd', 'd') THEN DATEADD(day, (ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) ) * #interval, #startDate)
WHEN #dateInterval IN ('hour', 'hh') THEN DATEADD(hour, (ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) ) * #interval, #startDate)
WHEN #dateInterval IN ('minute', 'mi', 'n') THEN DATEADD(minute, (ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) ) * #interval, #startDate)
WHEN #dateInterval IN ('second', 'ss', 's') THEN DATEADD(second, (ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) ) * #interval, #startDate)
END
FROM
cte_n3 a CROSS JOIN cte_n3 b
)
SELECT
c.BegOfRange,
c.EndOfRange
FROM
cte_Calendar c;
GO