title: StrongTypingException when setting column value
body: <p>Can anyone please tell me why I get a StrongTypingException when ASSIGNING a value to a column in a strongly typed DataTable? (I understand why I get it if I were to READ the column with DBNull value)</p>
  
  <p>In the example below I'm trying to assign a value from one DataTable to another (all columns in the example are of type <strong>Int32</strong>). I can assign a value to the 'newOrderRow.items' column but when I do the same with the 'newOrderRow.debcode' column an Exception is thrown! Why?!</p>
  
  <p><strong><em>Some of the things I've tried so far (without any luck):</em></strong><br>
  - Assign hard coded value instead of 'calclineRow.debcode'<br>
  - Call newOrderRow.SetdebcodeNull() before assigning another value<br>
  - Changed DefaultValue property on 'debcode' column in 'orderrows' table from DBNull to -1 and <em>it STILL throws the Exception and says it's DBNull !!!</em></p>
  
  <pre><code>myDataSet.orderrowsRow newOrderRow;
  
  foreach (MyDataSet.calclinesRow calclineRow in myDataSet.calclines)
  {
      newOrderRow = myDataSet.orderrows.NeworderrowsRow();  //Create new 'orderrows' row
  
      //Assign values from one DataTable to another
      if (!calclineRow.IsitemsNull())
          newOrderRow.items = calclineRow.items;  //calclineRow.items == 1. Assignment successful
      if (!calclineRow.IsdebcodeNull()) 
          newOrderRow.debcode = calclineRow.debcode; //calclineRow.debcode == 556. Assignment raises System.Data.StrongTypingException ! (See message below)
  
  
      myDataSet.orderrows.AddorderrowsRow(newOrderRow);
  }
  
  /*Exception Message:
  =====================
  
  System.Data.StrongTypingException: The value for column 'debcode' in table 'orderrows' is DBNull. 
  ---&gt; System.InvalidCastException: Specified cast is not valid. 
  at MyProject.MyDataSet.orderrowsRow.get_debcode() in Q:\MyProjFolder\DataSets\MyDataSet.Designer.cs:line 21680
  */
  </code></pre>