title: oracle sql developer: 00904. 00000 - "%s: invalid identifier". Where is my fault?
body: <p>I am trying find my fault. 
  I am getting this error message:</p>
  
  <blockquote>
    <p>SQL-Fehler: ORA-00904: "S1"."PARTNO": ungültiger Bezeichner
    00904. 00000 -  "%s: invalid identifier"</p>
  </blockquote>
  
  <p>I have checked my database and all tables exist. </p>
  
  <p>Here is my sql code:</p>
  
  <pre><code>select s1.*
   , p.city as "Produktionsort" 
   , p.partname
  from (select count(s.partno) as "Anzahl_Produktarten"
          , s.partno as "Partno" 
        from company.supp_part_job s 
        group by s.partno ) s1
   , company.part p 
  where s1.partno IN (select p1.partno from company.part p1 where p1.city != 'London') 
     and p.partno = s1.partno 
  group by s1.partno
  </code></pre>