SSRS Multiple Field Values Not Passing As Parameters To Drilldown Report - reporting-services

Question

I have not found a suitable answer to my following problem after much searching.
I have a summary report which shows the total number of appointments by month grouped by specialty name and diagnosis.
Specialty_Name Diagnosis Code Feb Mar Apr
Neurology G35X 0 3 4
G379 8 5 7
Total For Spec 8 8 11
Rheumatology H051 4 9 2
M059 6 10 3
Total For Spec 10 19 5
When I click on the field (ie 11 for Neurology Total For Spec, Apr), which is =COUNT((Fields!Appointment_ID.Value), I want to pass each of the Appointment_IDs to a sub query as the parameter to display the associated client details. However, when I prepare the sub query and drill down report in a manner that I have used before I am only getting the result of the first Appointment_ID; not each one.
The sub query report is set up with the parameter #Appointment_ID VARCHAR(MAX) and a WHERE clause:
CAST(App.App_ID AS VARCHAR(MAX)) in (
SELECT * FROM Serve1.dbo.CreateParameterTable(#Appointment_ID,',')
)
The CreateParameterTable is a function on our server which should handle the string from the summary report and does so on other reports.
(
#StringInput NVARCHAR(MAX)
, #SplitBy NCHAR(1)
)
RETURNS #OutputTable TABLE ( [String] NVARCHAR(36) )
AS
BEGIN
DECLARE #String NVARCHAR(36)
WHILE LEN(#StringInput) > 0
BEGIN
SET #String = LEFT(#StringInput,
ISNULL(NULLIF(CHARINDEX(#SplitBy, #StringInput) - 1,
-1), LEN(#StringInput)))
SET #StringInput = SUBSTRING(#StringInput,
ISNULL(NULLIF(CHARINDEX(#SplitBy, #StringInput),
0), LEN(#StringInput))
+ 1, LEN(#StringInput))
INSERT INTO #OutputTable ( [String] )
VALUES ( #String )
END
If I manually type in multiple Appointment_IDs to my drill down report I get the expected result. Therefore it appears that either my Summary Report is not passing out a string or it is not being handled correctly by the function or the sub report does not like the output of the function Which as I have said works on other reports we have written. I'm stumped.

Answer 1

How to begin troubleshooting your specific problem
Because you've said you can get the subreport working by supplying a string of values as desired, then it appears the problem is with the report providing the delimited string. Before you can fix the issue, you need to see the delimited string being passed to the subreport - so add it to the tablix. Use the same function you're using to reference the value in the "Go to Report" action and add it as a tooltip to each count. That way you can see the string being prepared and tweak your logic until it comes out correctly.
How I would solve your problem
What you're trying to accomplish as a multi-valued parameter is, as I see it, unnecessarily complicated.
In your tablix, you have a set way of organizing the results. You have specialty name, diagnosis, and month (presumably of the diagnosis or date served).
That's three parameters you can pass through to a sub-report. Using similar sql logic as exists in your main report, you can isolate those 11 simply by knowing the values of those three fields plus the year. Obviously, you will need to do some work to find diagnosis/service dates that fall into a given month, but that's not too hard:
Where Month(Date_of_Service) = #Month
and Year(Date_of_Service) = #Year
and Specialty_Name = #Specialty
and Diagnosis_Code = #Diagnosis