title: OleDbDataAdapter and column casting while importing Excel to ASP.NET
body: <p>I'm importing an excel using c#. But CustomerOrderNR column contains these kind values:</p>
  
  <pre><code>20283
  20213
  20625
  50749-50
  30687
  31975
  82253
  </code></pre>
  
  <p>But when I execute these codes:</p>
  
  <pre><code>    string QTam = @"SELECT Date, [Serial Number], [Status Code], Description, CustomerOrderNR FROM [Sheet1$]";
  
      DataSet ds = new DataSet();
      OleDbDataAdapter cmd = new OleDbDataAdapter(QTam, strConn);
      cmd.Fill(ds, "orders");
  </code></pre>
  
  <p>It is returning CustomerOrderNR column in System.Double data type.
  I want to change datatable column type but then it return exception like:</p>
  
  <pre><code>Cannot change DataType of a column once it has data.
  </code></pre>
  
  <p>Can't I change DataType of Column from Double to String in SQL statement?</p>