title: MySql IN clauses, trying to match IN list of tuples
body: <p>I am trying to select duplicate records based on a match of three columns.  The list of triples could be very long (1000), so I would like to make it concise.</p>
  
  <p>When I have a list of size 10 (known duplicates) it only matches 2 (seemingly random ones) and misses the other 8.  I expected 10 records to return, but only saw 2.</p>
  
  <p>I've narrowed it down to this problem:</p>
  
  <p>This returns one record.  Expecting 2:</p>
  
  <pre><code>select * 
  from ali
  where (accountOid, dt, x) in
  (
    (64, '2014-03-01', 10000.0), 
    (64, '2014-04-23', -122.91)
  )
  </code></pre>
  
  <p>Returns two records, as expected:</p>
  
  <pre><code>select * 
  from ali
  where (accountOid, dt, x) in ( (64, '2014-03-01', 10000.0) )
  or (accountOid, dt, x) in ( (64, '2014-04-23', -122.91) )
  </code></pre>
  
  <p>Any ideas why the first query only returns one record?</p>