title: Alter data type of a column to serial
body: <p>In pgsql, is there a way to have a table of several values, and choose one of them (say, other_id), find out what its highest value is and make every new entry that is put in the table increment from that value.</p>
  
  <p>I suppose this was just too easy to have had a chance of working..</p>
  
  <pre><code>ALTER TABLE address ALTER COLUMN new_id TYPE SERIAL
  
  ____________________________________ 
  ERROR:  type "serial" does not exist
  </code></pre>
  
  <p>Thanks much for any insight!</p>