title: MySQL Conditional Joins
body: <p>I want to conditionally join on multiple columns in mysql.  Basically, I want to look that if it table A doesn't match table B of that column I'd like to try and get it to match on the next one.  My first check would be:</p>
  
  <pre><code>Join A.Acct = B.Acct.  
  </code></pre>
  
  <p>If it fails to join during that process if table B doesn't have a record to match A then do</p>
  
  <pre><code>Left Join A.Phone=B.Phone OR LEFT Join A.Phone=B.Phone2 OR 
  </code></pre>
  
  <p>LEFT JOIN 
      A.Phone=B.PHONE3 </p>