title: Sql Query select all rows not in another set
body: <p>Suppose I have this table: </p>
  
  <pre><code>sett_tb_plant_trans
  
  (pk)uidplanttrans  field1  stoptime
  ---------------------------------   
  x                  1       1/1/2000
  y                  1       null 
  z                  2       1/1/2000
  k                  2       1/1/2000
  v                  3       null
  j                  4       null
  </code></pre>
  
  <p>I would like to select just <code>z</code> and <code>k</code> because them have the <code>stoptime</code> filled for all the rows and same "key" for the field1.</p>
  
  <p>i did this query :</p>
  
  <pre><code> select 
     field1 from sett_tb_plant_trans 
   where uidplanttrans not in 
     (select uidplanttrans from sett_tb_plant_trans where stoptime is null)
  </code></pre>
  
  <p>but returns some <code>field1</code>  that have some rows with <code>stoptime</code> null</p>
  
  <p>why?</p>