Issues passing drillthrough parameters from a multi-level tablix in SSRS 2008 R2

Question

Hello,
I am really struggling with trying creating a drillthrough report that starts with a matrix (tablix)  and passing those  parameters. I am using SSRS 2008 R2.
Here's my scenario:
I have a matrix that has mulitple levels where you can drill down. Here an example with all the levels open:  
Active
Term
Leave
Total
128
88
121
United States
110
80
85
New York
65
30
57
Manhattan
10
6
9
Buffalo
20
23
4
Albany
35
1
44
Texas
45
50
28
Dallas
40
30
22
Houston
5
20
6
France
18
8
36
Centre
18
8
36
Blois
7
2
8
Druex
6
1
15
Tours
5
5
13
I want to drillthrough to another report - Detail Report. As I understand it, I would click the 65 for New York and I would see the detail for the 65 Active people. If I click the 2 under Blois, I would see the 2 terminated people in Blois. My understanding
for this to work, the Detail Report would need a a parameter for each of the level possibilities in the matrix that I could click: Country, State, City as well as the Status (Active, Term, Leave).
While I understand about passing parameters, what I don't understand is how to pass the parameters if they are blank. Let's say I clicked 65 for New York, I would need to pass State = New York  Status = Active. But the remaining parameters (Country
and City  would be null). I know Country doesn't need to be Null in this case.
My Detail Report has the parameters defaulted to Null, but whether I put the parameters in a Filter for the dataset or in the query itself, I cannot get it to ignore the Nulls.
As a crazy work-around (I think) I can put in the Where of the query  something along the lines of: this:
        and (a.Country in (@paramCountryCode) or NULL  in (@paramCountryCode) )
and I would need to do that for each parameter. Usually I have to use 'ALL' instead of NULL, I'm note sure why.
Additionally, in the Report Action of the Main Report, I need to pass those parameters for each level and their Status. I am also not clear whether or not I need to put in all the parameters on each of the levels (Country, State, City) of the matrix. And if
I do, do I need to make the expressions an IIF statement stating whether or not they are In Scope?
All the examples I was able to find, only showed one or maybe two parameters being passed. Doing the way I am trying, seems convoluted, error-prone and tedious. I really hope that I am wrong.
Is there a better way to approach drilltrough reports from a matrix when there are multiple levels?
Thank you for the help.
~J

Answer 1

Hi Jenna_Fire,
According to your description, you have a matrix contains total for each group on each level. Now your requirement is, when you click on any number (data field or total), it will go to the detail report which returns all the detail information of the people
within the group scope. For example, if you click on the total of Active users in United States, it will return the detail information of Active users in New York and Texas. Right?
In this scenario, we should set the parameter (@Country, @State, @City) allow multiple values in both main and detail report. And in Default Value (@Country, @State, @City), query out all distinct values. In the textbox which contains
those total values, when set use these parameters to run the report, we only need to pass the parameters of parent groups. For example, if we click on the total of Active users in New York, we only need to pass Country, State, Status to detail report, and
in the detail report, the City parameter will use all distinct values (Default Values) because we don't pass the City parameter. We have tested this case with sample data in our local environment. Here are steps and screenshots for your reference:
1. Create parameter Country, State, City and Status in both main report and detail report. Set both Available Value and Default Value get values from query (Create a dataset for each parameter, use "select distinct [column] from [table]" as query). Set allow
multiple values for parameter Country, State and City in both reports.
2. In corresponding textbox, pass appropriate parameters in go to report Action.
4. Filter data in detail report (in where clause or using filters).
5. Save and preview. It looks like below:
Reference:
Using Parameters to Connect to Other Reports
If you have any question, please feel free to ask.
Best Regards,
Simon Hou