title: Oracle left outer join query
body: <pre><code>select a,last_note_user,c,d,iso_src
  from X,Y,Z
  left outer join W
  ON (W.last_note_user=Z.userid AND W.user_ten=Y.iso_src)
  </code></pre>
  
  <p>when I am executing the above query it is giving me the error <code>"Y.iso_src" is a invalid identifier</code>.However,<code>Y.iso_src</code> is a valid identifier and it exist in the system table.
  Is something wrong with the above left outer join??
  Please help me out!!!</p>