title: simple joins between 2 mysql tables returning all results every time.. Help!
body: <p>I just imported a large amount of data into two tables. Let's call them shipments and returns.</p>
  
  <p>When trying to do a simple join (left or inner) based on any criteria in these two tables. query looks like it tries to do a cross join or find every combination instead of what the query should be pulling.</p>
  
  <p>each table has an PK id field, but there is not FK relationship between the two other than some shared field.</p>
  
  <p>I'm currently just trying to related them on shipment_id.</p>
  
  <p>I feel this is a simple answer. Am I missing a reference or something obvious that is causing this? Thanks!</p>
  
  <p>here's an example. This should returned under 100 rows. This instead returns hundreds of thousands.</p>
  
  <pre><code>SELECT r.*
  
  FROM returns as r
  
  left outer join shipments as s
  
  on r.shipment_id = s.shipment_id
  
  where r.date = '2011-06-20'
  </code></pre>