NS Reports

Here is something I wrote a while abck using collection picker. The tables for User logon data might not be correct for your database but the collection picker should work for you. Plus I am sure someone else has a faster way or different tables they would use but this is what I did.
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SELECT DISTINCT      
                      SUM(CASE WHEN AeXEvt_AeX_Client_LogOn.Event = 'Logon' THEN 1 ELSE 0 END) AS 'Logon',      
                      SUM(CASE WHEN AeXEvt_AeX_Client_LogOn.Event = 'Logoff' THEN 1 ELSE 0 END) AS 'Logoff', AeXEvt_AeX_Client_LogOn.[User],      
                      AeXEvt_AeX_Client_LogOn.Domain, vCollection.Name AS [Collection Name], Wrksta.Name AS [Computer Name]     
FROM         AeXEvt_AeX_Client_LogOn INNER JOIN     
                      Wrksta ON AeXEvt_AeX_Client_LogOn.WrkstaId = Wrksta.WrkstaId INNER JOIN     
                      CollectionMembership INNER JOIN     
                      vCollection ON CollectionMembership.CollectionGuid = vCollection.Guid ON Wrksta.Guid = CollectionMembership.ResourceGuid     
WHERE     (vCollection.[Guid] = '%Collections%')     
GROUP BY AeXEvt_AeX_Client_LogOn.[User], AeXEvt_AeX_Client_LogOn.Domain, AeXEvt_AeX_Client_LogOn.[Login Time], AeXEvt_AeX_Client_LogOn.Duration,      
                      vCollection.Name, Wrksta.Name     
ORDER BY [Computer Name]
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Now you need a global parameter added for collection picker which is using the %Collections% in the where statement.  So use the same name as the one in your code such as above as your name without the % signs, choose parameter type ' Item picker'  and then class filter 'collections' and you might want to type in a prompt to have them choose a collection.
Hope this helps you out.