title: COALESCE two dates returns binary?
body: <p>Why does <code>COALESCE(date1,date2)</code> return <code>Blob</code>(binary)? Both columns are of type <code>DATETIME</code>.</p>
  
  <p>Here's the complete sql query:</p>
  
  <pre><code>SELECT COALESCE( last_modified, date_purchased )As LastModifiedOrPurchased
  FROM Orders
  ORDER BY COALESCE( last_modified, date_purchased )DESC
  LIMIT 1;
  </code></pre>
  
  <p>I'm normally using SQL-Server as rdbms but need to write a synchronization tool. Now i'm trying to select one of two dates. If <code>last_modified</code> is null <code>date_purchased</code> should be returned.</p>
  
  <p>But even if there are multiple records where both dates are not null, the query returns just <code>Blob</code>. How to get the correct last date?</p>
  
  <p><strong>Edit</strong>: on <a href="http://sqlfiddle.com/#!8/35cae/3/0" rel="nofollow"><strong>SQL-Fiddle</strong></a> it is not reproducable with MySql 5.1.61 (i'm on 5.0.51).</p>