title: SQL delete orphan
body: <p>Assuming that all foreign keys have the appropriate constraint, is there a simple SQL statement to delete rows not referenced anywhere in the DB?</p>
  
  <p>Something as simple as <code>delete from the_table</code> that simply skip any rows with child record?</p>
  
  <p>I'm trying to avoid manually looping through the table or adding something like <code>where the_SK not in (a,b,c,d)</code>.</p>