DataTable TheDataTable = new DataTable();
TheConnString = "...";
TheStoredProcedureName = "...";
using ( SqlConnection conn = new SqlConnection(TheConnString) )
{
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandType = CommandType.StoredProcedure;
cmd.CommandText = TheStoredProcedureName;
SqlDataAdapter da = new SqlDataAdapter( cmd );
da.Fill(TheDataTable);
}

В результате получишь одну таблицу...