title: Table alias name scope in sub-select query
body: <p>Please have a look at the query below - I am getting invalid identifier <code>t1.oid</code> in the below inner query.</p>
  
  <p>I have column <code>oid</code> in <code>iclr_request t1</code></p>
  
  <pre><code>select t1.requestNo 
       , t2.routeDistance,
       , ( 
           select WM_CONCAT(crc7) as "TravCirc7s" 
             from (
                    select (
                             select crc7 
                               from dim_afi_dnld_stn_v1 
                              where stn_sys_nbr = t3.stn_sys_nbr 
                                and rownum=1
                            ) as crc7 
                     from iclr_trav_circ7 t3 
                    where request_oid = **t1.oid** 
                      and sub_route_index=0 
                      and station_type_oid = 1 
                    order by sequence
                  )
         ) 
    from iclr_request t1
       , iclr_summary_results t2
   where t1.oid = t2.request_oid
  </code></pre>