title: lastInsertId does not work in Postgresql
body: <p>I am using Postgresql, when I want to use PDO to retrieve the latest insertion ID, I got a problem. Here is my code:</p>
  
  <pre><code>$db-&gt;lastInsertId('columnName');
  </code></pre>
  
  <p>The error message says </p>
  
  <pre><code>SQLSTATE[42P01]: Undefined table: 7 ERROR: relation "columnName" does not exist
  </code></pre>
  
  <p>I guess I have some misunderstanding about "sequence object" stated in the PHP Manual.</p>
  
  <pre><code>Note:
  
  Returns the ID of the last inserted row, or the last value from a sequence object, 
  depending on the underlying driver. For example, PDO_PGSQL() requires you to specify the 
  name of a sequence object for the name parameter.
  </code></pre>
  
  <p>Currently, the "columnName" is the string of that auto-incremented attribute. Can anyone point out where I went wrong? Thanks.</p>