title: what is the correct way to read from a datarow if the cell might be null
body: <p>I have the following code which seems to blow up if the column in the datarow (dr) is null.  what is the correct way to parse out the value from the data row and handle null checks?</p>
  
  <pre><code>Person person = new Person()
  {
      FirstName = dr["FirstName"].ToString(),
      LastName = dr["LastName"].ToString(),
      BusinessPhoneNumber = dr["BusinessPhone"].ToString(),
  </code></pre>