title: in postgresql how to get the last 4 numbers from a field and copy it to a new field
body: <p>I'm trying to get the last four digits of the field "SERIAL8" and put that in a new field called "SS4".  Here is the query I'm trying to use but it isn't working.  I'm new at this, so any help would be appreciated</p>
  
  <pre><code>SELECT * FROM CUSTOMER_TABLE
  SUBSTRING (SERIAL,4,4) as 'SS4'
  
  
  
  
  CUSTOMER_TABLE
  +-----------------------+------------+----------+--+
  | "Complaint Full Date" |   Source   |  SERIAL  |  |
  +-----------------------+------------+----------+--+
  | 02/04/16              | DAPIS_CAIR | DG540732 |  |
  | 04/18/16              | DAPIS_CAIR | DG553384 |  |
  | 03/23/17              | RO         | DG559515 |  |
  | 03/29/16              | CAIR       | DG559781 |  |
  | 12/10/14              | DAPIS_CAIR | DG561621 |  |
  +-----------------------+------------+----------+--+
  </code></pre>