If Exists inside a CTE in SQl Server - sql

Question

I just want to know that How to write a CTE containing If Exists in SQl Server ?
I had tried to write a CTE below where i am Using If Exists Statement to select weather the record exist or not .In case if the record does not exist then i am assigning default value but i am getting error
'Incorrect syntax near the keyword 'if'
.' Please help me to fix this error and guide me to write this CTE.
Please find below the CTE which i had written:-
Alter procedure St_Proc_GetTeamProductionReport
#mindate DateTime,
#maxdate DateTIme,
#userID varchar(50)
as
Begin
set NoCount on;
with
ProductionCTE(CalendarDate,RoleID,UserID,UserECode,UserName,ImmediateSupervisor,NatureOfWorkName,RegionProjectName,CountyName,WorkTypeName,TaskName,VolumneProcessed,TimeSpent,Comment)
as
(
if exists
(
select P.CalendarDate,U.RoleID,U.UserID,U.UserECode,U.UserName,U.ImmediateSupervisor,N.NatureofWorkName,
R.RegionProjectName,C.Countyname,W.WorktypeName,T.TaskName,P.VolumeProcessed,P.Timespent,P.Comment
from production P inner join NatureOfWork N
on N.NatureofWorkID=P.natureofworkid
inner join dbo.RegionAndProjectInfo R
on R.RegionProjectID=P.RegionProjectID
inner join county C
on C.countyid=P.countyid
inner join worktype W
on W.Worktypeid=P.worktypeID
inner join task T
on T.taskid=P.TaskID
inner join UserInfo U
on U.Userid=P.userid
where P.userid=#userID and ( convert(varchar, P.CalendarDate, 101) ) between (
convert(varchar, #mindate, 101) ) and ( convert(varchar, #maxdate, 101) )
)
else
(
Select '2012-09-14 13:41:52' as CalendarDate,
2 as RoleID,'938' as UserID,
(select Userecode from Userinfo where userid=#userID) as UserECode,
(select UserName from Userinfo where userid=#userID)as UserName,
(select ImmediateSupervisor from Userinfo where userid=#userID)as ImmediateSupervisor,
'BP' as NatureOfWorkName,
'CO Processing' as RegionProjectName,
'Adams' as CountyName,
'Quality' as WorkTypeName,
'Corrections ' as TaskName,
5 as VolumneProcessed,
'01:00' as TimeSpent,
'test' as Comment
)
union all
select P.CalendarDate,U.RoleID,U.UserID,U.UserECode,U.UserName,U.ImmediateSupervisor,N.NatureofWorkName,
R.RegionProjectName,C.Countyname,W.WorktypeName,T.TaskName,P.VolumeProcessed,P.Timespent,P.Comment
from production P inner join NatureOfWork N
on N.NatureofWorkID=P.natureofworkid
inner join dbo.RegionAndProjectInfo R
on R.RegionProjectID=P.RegionProjectID
inner join county C
on C.countyid=P.countyid
inner join worktype W
on W.Worktypeid=P.worktypeID
inner join task T
on T.taskid=P.TaskID
inner join UserInfo U
on U.Userid=P.userid
inner join ProductionCTE
on U.ImmediateSupervisor=ProductionCTE.UserECode
where P.IsTaskCompleted=1 and ( convert(varchar, P.CalendarDate, 101) ) between (
convert(varchar, #mindate, 101) ) and ( convert(varchar, #maxdate, 101) )
)
select distinct CONVERT(VARCHAR,CalendarDate,20) as CalendarDate,UserECode,UserName,NatureOfWorkName,RegionProjectName,CountyName,WorkTypeName,TaskName,VolumneProcessed,TimeSpent,Comment from ProductionCTE where RoleID=1
end
GO
When i am removing this If Exist statement then the CTE is working fine but after adding the IF Exists statement it is having error.

Answer 1

You can't use IF EXISTS in this way. A common table expression must only contain a single select statement, it's not possible to say if condition SELECT THIS else SELECT THAT.
It looks like you are trying to add an additional created row to a resultset returned by a query. You could achieve this by implementing the CTE as a table-valued function that would return the single new row.
http://msdn.microsoft.com/en-gb/library/ms191165(v=sql.105).aspx

Answer 2

If you want to construct a UNION where you only get a result from the second SELECT if the first SELECT returns no rows, you can achieve this using RANK(). So, you can place your real query in the first SELECT and the desired default values in the second, and achieve the results you want.
I don't have your tables and data, so I'm not going to attempt to re-write your query. But I'll illustrate with this:
;With WithDefaults as (
select name,0 as Rank from sys.objects
union all
select 'abc',1 --Default if no results
), Ranked as (
select *,RANK() OVER (ORDER BY Rank) as Rnk from WithDefaults
)
select * from Ranked where Rnk = 1
Returns (on a mostly empty DB I tried it on) 98 results, of which none had the name abc. If we force the first SELECT to return no results:
select name,0 as Rank from sys.objects where 1 = 2
We now get a single row result with the name abc.
Hopefully, you can see how this could apply to your original query.

Answer 3

You can't use IF EXISTS in CTE. But you can modify logic of function
Example:
alter procedure St_Proc_GetTeamProductionReport
#mindate DateTime,
#maxdate DateTIme,
#userID varchar(50)
as
Begin
set NoCount on;
;with
ProductionCTE(CalendarDate,RoleID,UserID,UserECode,UserName,ImmediateSupervisor,NatureOfWorkName,RegionProjectName,CountyName,WorkTypeName,TaskName,VolumneProcessed,TimeSpent,Comment)
as
(
select P.CalendarDate,U.RoleID,U.UserID,U.UserECode,U.UserName,U.ImmediateSupervisor,N.NatureofWorkName,
R.RegionProjectName,C.Countyname,W.WorktypeName,T.TaskName,P.VolumeProcessed,P.Timespent,P.Comment, 1 AS cnt
from production P inner join NatureOfWork N
on N.NatureofWorkID=P.natureofworkid
inner join dbo.RegionAndProjectInfo R
on R.RegionProjectID=P.RegionProjectID
inner join county C
on C.countyid=P.countyid
inner join worktype W
on W.Worktypeid=P.worktypeID
inner join task T
on T.taskid=P.TaskID
inner join UserInfo U
on U.Userid=P.userid
where P.userid=#userID and ( convert(varchar, P.CalendarDate, 101) ) between (
convert(varchar, #mindate, 101) ) and ( convert(varchar, #maxdate, 101) )
UNION ALL
Select '2012-09-14 13:41:52' as CalendarDate,
2 as RoleID,'938' as UserID,
(select Userecode from Userinfo where userid=#userID) as UserECode,
(select UserName from Userinfo where userid=#userID)as UserName,
(select ImmediateSupervisor from Userinfo where userid=#userID)as ImmediateSupervisor,
'BP' as NatureOfWorkName,
'CO Processing' as RegionProjectName,
'Adams' as CountyName,
'Quality' as WorkTypeName,
'Corrections ' as TaskName,
5 as VolumneProcessed,
'01:00' as TimeSpent,
'test' as Comment, 0
), ProductionCTE2 AS
(
SELECT TOP(SELECT CASE WHEN COUNT(*) = 0 THEN 1 ELSE COUNT(*) END FROM ProductionCTE WHERE cnt = 1)
CalendarDate,RoleID,UserID,UserECode,UserName,ImmediateSupervisor,NatureofWorkName,
RegionProjectName,Countyname,WorktypeName,TaskName,VolumeProcessed,Timespent,Comment
FROM ProductionCTE2
union all
select P.CalendarDate,U.RoleID,U.UserID,U.UserECode,U.UserName,U.ImmediateSupervisor,N.NatureofWorkName,
R.RegionProjectName,C.Countyname,W.WorktypeName,T.TaskName,P.VolumeProcessed,P.Timespent,P.Comment
from production P inner join NatureOfWork N
on N.NatureofWorkID=P.natureofworkid
inner join dbo.RegionAndProjectInfo R
on R.RegionProjectID=P.RegionProjectID
inner join county C
on C.countyid=P.countyid
inner join worktype W
on W.Worktypeid=P.worktypeID
inner join task T
on T.taskid=P.TaskID
inner join UserInfo U
on U.Userid=P.userid
inner join ProductionCTE
on U.ImmediateSupervisor=ProductionCTE.UserECode
where P.IsTaskCompleted=1 and ( convert(varchar, P.CalendarDate, 101) ) between (
convert(varchar, #mindate, 101) ) and ( convert(varchar, #maxdate, 101) )
)
select distinct CONVERT(VARCHAR,CalendarDate,20) as CalendarDate,UserECode,UserName,NatureOfWorkName,RegionProjectName,CountyName,WorkTypeName,TaskName,VolumneProcessed,TimeSpent,Comment
from ProductionCTE2
where RoleID=1
end