title: Conversion of SQL Server datetime column to 24h format failing
body: <p>I have a SQL Server 2008 table with a <code>DateTime</code> column that I'd like to convert into 24h format.</p>
  
  <p>The canonical guidance is to use something along the lines of:</p>
  
  <pre><code>select CONVERT(datetime, GetDate(), 121)
  </code></pre>
  
  <p>which yields:</p>
  
  <pre><code>2012-01-24 15:22:27.340
  </code></pre>
  
  <p>Perfect. Ok, so applying this knowledge, let's replace <code>GetDate()</code> with a column for the <code>CONVERT</code> expression:</p>
  
  <pre><code>select top(5) CONVERT(datetime, LogTable.Timestamp, 121) from LogTable
  order by LogTable.Id DESC
  </code></pre>
  
  <p>And we get:</p>
  
  <pre><code>2012-01-24 03:25:47.933
  2012-01-24 03:25:46.917
  2012-01-24 03:25:46.547
  2012-01-24 03:25:46.543
  2012-01-24 03:25:46.543
  </code></pre>
  
  <p>What am I doing wrong? How should the expression be crafted to get <code>CONVERT</code> to work on a column as opposed to the output of the <code>GetDate()</code> function?</p>