title: How to simplify sql statement
body: <p>I have the following query -- </p>
  
  <pre><code>select * from main_iteminstance where master_id=33568
    or tv_series_id  in 
  (select id from main_iteminstance where master_id=33568)
  </code></pre>
  
  <p>How would this best be simplified?</p>
  
  <p>Basically, what I am trying to get is:</p>
  
  <pre><code>ids = select id from main_iteminstance where master_id=33568
  child_ids = select id from main_iteminstance where tv_series_id in ids
  my_answer = ids + child_ids
  </code></pre>