Using maxrecursion in INSERT query - sql-server

Question

Thank you for looking at this.
I have two CTE tables that generate duty times, the calculations are convoluted so wont bother you with them.
Here is the SQL (Simplified)
DECLARE #StartDate Datetime -- Start Date for the Duties to be generated
DECLARE #PatternStartPoint int --Start Point in Pattern eg 3 -
DECLARE #PatternSize int --The length of the shift pattern
DECLARE #User int
SET #User = 1111;
SET #PatternSize = 3;
SET #DaysRequired=16; --Testing assume 16
SET #StartDate = DATEADD(dd, 0, DATEDIFF(dd, 0, GETDATE())); --for testing use today
SET #PatternStartPoint =3;
--Get Job Duty Pattern
WITH Pattern (P_DayNumber, P_DayType, P_Start, P_End)
AS
(
Select D_DayNumber,D_Type,D_Start,D_End
from dbo.Tbl_Jobs as J
join dbo.Tbl_Patterns as P
on J.J_PatternID = P.Pattern_ID
join dbo.Tbl_PatternDetails as D
on P.Pattern_ID=d.D_Pattern_ID
)
,
--Get DateList
Datelist (MyDate, DayNumber) AS
(
SELECT #StartDate AS MyDate, #PatternStartPoint as DayNumber
UNION ALL
Select MyDate + 1, (DayNumber+1) - (CAST((Daynumber+1)/(#PatternSize+.01) as int)*#PatternSize) --% (#PatternSize)
FROM Datelist
WHERE MyDate < (#Startdate + #DaysRequired)-1
)
INSERT INTO [IDAHO].[dbo].[Appointments]
([Subject]
,[Description]
,[Start]
,[End]
,[RoomID]
,[UserID]
)
(
SELECT
'Standard Work Pattern'
,'IDAHO Generated on ' + CONVERT(nvarchar(20),getdate())
,mydate + p.P_Start
,mydate + p.P_End
,1
,#User as A_User
FROM Datelist as d
join Pattern as p
on p.P_DayNumber=d.DayNumber
Where mydate + p.P_Start is not null
OPTION (MAXRECURSION 0)
)
I am getting an error with the MAXRECURSION line, if I remove the line and try to generate more than 100 'Duties' it errors (being the default value).
If I Change the last statement to a simple select it seems to work??? as shown below
DECLARE #StartDate Datetime -- Start Date for the Duties to be generated
DECLARE #PatternStartPoint int --Start Point in Pattern eg 3 -
DECLARE #PatternSize int --The length of the shift pattern
DECLARE #DaysRequired int --The length of the shift pattern
DECLARE #User int
SET #User=1111;
SET #PatternSize = 3;
SET #DaysRequired=160; --Testing assume 16
SET #StartDate = DATEADD(dd, 0, DATEDIFF(dd, 0, GETDATE())); --for testing use today
SET #PatternStartPoint =3;
--Get Job Duty Pattern
WITH Pattern (P_DayNumber, P_DayType, P_Start, P_End)
AS
(
Select D_DayNumber,D_Type,D_Start,D_End
from dbo.Tbl_Jobs as J
join dbo.Tbl_Patterns as P
on J.J_PatternID = P.Pattern_ID
join dbo.Tbl_PatternDetails as D
on P.Pattern_ID=d.D_Pattern_ID
)
,
--Get DateList
Datelist (MyDate, DayNumber) AS
(
SELECT #StartDate AS MyDate, #PatternStartPoint as DayNumber
UNION ALL
Select MyDate + 1, (DayNumber+1) - (CAST((Daynumber+1)/(#PatternSize+.01) as int)*#PatternSize) --% (#PatternSize)
FROM Datelist
WHERE MyDate < (#Startdate + #DaysRequired)-1
)
SELECT
'Standard Work Pattern'
,'IDAHO Generated on ' + CONVERT(nvarchar(20),getdate())
,mydate + p.P_Start
,mydate + p.P_End
,1
,#User as A_User
FROM Datelist as d
join Pattern as p
on p.P_DayNumber=d.DayNumber
Where mydate + p.P_Start is not null
OPTION (MAXRECURSION 0)
Have I put the command in the wrong place?
Why does it work with select but not insert?
Thank you

Answer 1

I think its because the CTE doesn't finally get assembled into a result set until the final select is run, which is why tour second query works. To make the insert work, try:
DECLARE #StartDate Datetime -- Start Date for the Duties to be generated
DECLARE #PatternStartPoint int --Start Point in Pattern eg 3 -
DECLARE #PatternSize int --The length of the shift pattern
DECLARE #DaysRequired int --The length of the shift pattern
DECLARE #User int
SET #User=1111;
SET #PatternSize = 3;
SET #DaysRequired=160; --Testing assume 16
SET #StartDate = DATEADD(dd, 0, DATEDIFF(dd, 0, GETDATE())); --for testing use today
SET #PatternStartPoint =3;
--Get Job Duty Pattern
INSERT INTO [IDAHO].[dbo].[Appointments]
([Subject]
,[Description]
,[Start]
,[End]
,[RoomID]
,[UserID]
)
select *
from
(
SELECT
'Standard Work Pattern' [Subject]
,'IDAHO Generated on ' + CONVERT(nvarchar(20),getdate()) [Description]
,mydate + p.P_Start [Start]
,mydate + p.P_End [End]
,1 [RoomID]
,#User [UserID]
FROM
(
SELECT #StartDate AS MyDate, #PatternStartPoint as DayNumber
UNION ALL
Select MyDate + 1, (DayNumber+1) - (CAST((Daynumber+1)/(#PatternSize+.01) as int)*#PatternSize) --% (#PatternSize)
FROM Datelist
WHERE MyDate < (#Startdate + #DaysRequired)-1
) as d
join
(
Select D_DayNumber,D_Type,D_Start,D_End
from dbo.Tbl_Jobs as J
join dbo.Tbl_Patterns as P
on J.J_PatternID = P.Pattern_ID
join dbo.Tbl_PatternDetails as D
on P.Pattern_ID=d.D_Pattern_ID
) as p
on p.P_DayNumber=d.DayNumber
Where mydate + p.P_Start is not null
) x;
That might work.
(Expanded as requested)
(Amended to remove CTEs)