title: rownum in Subquery
body: <p>I was wondring why this doesn't work:</p>
  
  <pre><code>SELECT 
    (
      SELECT COALESCE(MAX(a.LaufNr),0) + TBL.Rownum
      FROM schemaB.PersonRelatedTbl A
      WHERE A.Persid = Tbl.Persid
    )
    , Tbl.Some_Other_Attributs
  FROM schemaA.PersonRelatedTbl TBL 
  WHERE ...
  </code></pre>
  
  <p>This <code>+ TBL.Rownum</code> gives an error<br>
  why?</p>
  
  <p>greets
  Auro</p>