title: SSRS filter parameters
body: <p>I have "Country" filter dropdown list in ssrs report. This contains all countries and it is a multiselect dropdownlist. If user selects "All" the reports sends all country names comma separated to a storedprocedure where I have the query to display data. In stored procedure i split the values and compare the data. No issues so far. Now what I want is, If user selects "All", i don't need to pass all comma separated values to SP, instead pass null. So in my sp i don't have to split or join the tables. The problem is identifying whether the user has selected the "All" check box in the report criteria.Is there a way to find this whether the "All" is selected?</p>
  
  <p>the country is dynamic, so i don't have a lookup value to count all countries. 
  Parameters!Country.Count == 10 -- I can't do that because I don't know the 10.</p>