title: DBNull in non-empty cell when reading Excel file through OleDB
body: <p>I use OleDB to read an Excel file. One of the columns has a "Common" format and contains both strings with letters and values consisting of numbers only. String values are retrieved without problem, but pure numerical values are retrieved as <code>DBNull</code>.</p>
  
  <p>How to solve?</p>
  
  <p>I use the following connection string to open <strong>Excel 2003 file</strong> (xls):</p>
  
  <pre><code>"Provider=Microsoft.Jet.OLEDB.4.0;
   Data Source=C:\\file.xls;
   Extended Properties=\"Excel 8.0;HDR=Yes;IMEX=1\""
  </code></pre>