title: Are these SQL queries identical - if not whats the difference
body: <p>Assuming the proper tables are in place - what is the difference between the two queries - when would they return different results</p>
  
  <pre>
  select *
  from quiz_user qu
  join quiz_topic qt on qu.quiz_id = qt.quiz_id and qt.topic_id=44
  where qu.user_id=9
  
  select *
  from quiz_user qu
  join quiz_topic qt on qu.quiz_id = qt.quiz_id 
  where qu.user_id=9
  and qt.topic_id=44
  </pre>
  
  <p>Thanks</p>