title: Datatable Compute Method Convert string column to date
body: <p>I have a column in datatable having dates with format <code>dd/MM/yyyy HH:mm</code>. I fill the datatable using the code below which is common for more than 1 select statements so i cannot specify column and their datatype before filling the datatable. Any manipulation after filling the data is acceptable to me.</p>
  
  <pre><code>data_adapt = New OracleDataAdapter(query, OraConn)
  dt = New DataTable
  data_adapt.Fill(dt)
  </code></pre>
  
  <p>For paging i create a copy of the datatable using skip and take as below</p>
  
  <pre><code>dtLineupCopy = New DataTable
  dtLineupCopy = dtLineup.AsEnumerable().Skip(startRows).Take(pageSize)).CopyToDataTable()
  </code></pre>
  
  <p>Now the issue is when I use Compute method it doesn't treat the column values as date type and returns some random date value from the column instead of minimum value.</p>
  
  <pre><code>Arvdate = dtLineupCopy.Compute("Min(Arrivaldate)", "")
  </code></pre>
  
  <p>Is there a way to convert the datatype for the column?</p>
  
  <p>Also tried adding a new column of datetime type but it throws error <code>System.FormatException: String was not recognized as a valid DateTime</code></p>
  
  <pre><code>dtLineupCopy.Columns.Add("ArvDate", getType(DateTime), "CONVERT(Arrivaldate, 'System.DateTime')")
  </code></pre>
  
  <p>Data in Arrivaldate column of dtLineupCopy.</p>
  
  <p>22/09/2012 01:02<br>
   27/09/2012 17:01<br>
   1/10/2012 1:02<br>
   13/10/2012 07:26<br>
   14/10/2012 19:47<br>
   20/10/2012 00:00<br>
   20/10/2012 00:00</p>