title: left join with OR clause
body: <p>I have 2 tables, shown simplified below:</p>
  
  <pre><code>Table 1: | id | somedata | checkcode
  Table 2: | id | somedata | checkcode1 | checkcode2
  </code></pre>
  
  <p>I would need to left join the second one where checkcode1 OR checkcode2 is like checkcode. I tried to make two distinct left join, but that did not work, since it included double the data.</p>
  
  <p>What I would need is something like this:</p>
  
  <pre><code>Select * from Table1 as t1     
  LEFT JOIN Table2 as t2 
  on t1.checkcode = (t2.checkcode1 OR t2.checkcode2)     
  </code></pre>
  
  <p>Is this possible?</p>