title: SQL Server : change column to not null in a very large table
body: <p>I am trying to change a column to <code>not null</code> on a 3.5 gb table (SQL Server Express). </p>
  
  <p>All rows contain values in the table.</p>
  
  <p>I remove the check box from <code>allow null</code> and click save. </p>
  
  <p>I get: </p>
  
  <blockquote>
    <p>Unable to modify table.<br>
    Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.</p>
  </blockquote>
  
  <p>How can I overcome this?</p>