Visual Studio 2005 Dynamic Parameter passing

Hello experts,  noobie here at VS2005, so I apologize in advance.

I have a script where the user must choose a practice name, and then I would like to filter the next parameter to show only provider based in that practice at run-time.

So, I have:
Table: order
id                  practice_name             doc
1                   Main st                         Smith
2                   Main st                         Jones
3                   Canal st                        Parker


my script:

select id, practice_name, doc
from order
where practice_name = @Practice_Name


My @Practice_name is a dataset query which is:
select distinct practice_name from practice

and my @doc is a dataset query which is:
select distinct doc from providers

I would like to, in theory, have my @Doc variable be dependent on what is chosen in my @practice_name variable.  Something like:

my @doc would a dataset query which is:
select distinct doc from providers
where doc_practice = @practice_name

So in the parameter drop-down when you run the report, if you chose "Main St" as your practice, you would get only "Smith" and "Jones" in your drop down to choose from.

How can I go about configuring that?

Thanks!