title: liquibase <insert> : Insert current date
body: <p>I am trying to insert data using liquibase insert tag. It works fine when I am inputing a number to value tag .
  But I am looking for a simple function that will take care of default date (current DateTime of database) even when I don't have it as part of my table definition. </p>
  
  <p>Eg:</p>
  
  <pre><code>&lt;changeSet id="abc_1" author="Me"&gt;
  &lt;insert tableName="Emp" schemaName="XYZ"&gt;
      &lt;column name="name" value="Me"/&gt;
      &lt;column name="create_date" value ="1328055111692"/&gt;
      &lt;column name="profile_last_update" value="currentDateTimeFunction"/&gt;
      &lt;column name="group_name" value="BlahBlah"/&gt;
  &lt;/insert&gt;
  &lt;/changeSet&gt;
  </code></pre>
  
  <p>here <code>&lt;column name="create_date" value ="1328055111692"/&gt;</code> works fine and it gets inserted in to the database. I also tried using <code>&lt;defaultValueDate&gt;</code> and <code>&lt;valueDate&gt;</code> but they also need some date input in specified format.</p>
  
  <p>I am looking for some function like <strong>currentDateTimeFunction</strong> that would be converted to UNIX_TIMESTAMP() or SYSDATE or now() based on type of database I am using. Please help me.</p>
  
  <p>Thank you,
  Ramya</p>