title: SQL Server 2008 timestamp data type
body: <p>At present I have a column with datatype <code>datetime</code> with default constraint. Now I want to alter as a data type as time stamp.</p>
  
  <pre><code>alter table tblname
  alter column date_modified timestamp not null
  </code></pre>
  
  <p>My original requirement is whenever I update a record the column called <code>date_modified</code> should update with recent time .</p>
  
  <p>This is same functionality which is working in MYSQL with datatype <code>TIMESTAMP</code> and default value <code>CURRENT_TIMESTAMP</code></p>
  
  <p>How can I perform in this in SQL Server 2008??</p>