title: update query with self join
body: <p>I have a table data as below in oracle 11g,</p>
  
  <pre><code> PRD_ID    PATTERN                       TXN    FLAG
   1       "UPDATE TBL1 SET TYPE='B'"      5      Y
   1       "UPDATE TBL1 SET TYPE='B'"      5      N
   2       "UPDATE TBL1 SET TYPE='B'"      6      Y
   3       "UPDATE TBL1 SET TYPE='B'"      5      Y
  </code></pre>
  
  <p>What I want to do is to remove leading and trailing double quotes from column pattern, and I could do it by trim (both '"' from (PATTERN)). My question is how could I apply it in the update statement so the table will update to below</p>
  
  <pre><code> PRD_ID    PATTERN                       TXN    FLAG
     1       UPDATE TBL1 SET TYPE='B'      5      Y
     1       UPDATE TBL1 SET TYPE='B'      5      N
     2       UPDATE TBL1 SET TYPE='B'      6      Y
     3       UPDATE TBL1 SET TYPE='B'      5      Y
  </code></pre>