title: How to update values in column which shows only once?
body: <p>How to update id values for only those items that appear only once in item column?</p>
  
  <p>Table1</p>
  
  <pre><code>id | item | price
  -------------
  10 | pen  | 10  
  20 | pen  | 10   
  30 | pen  | 10
  30 | copy | 10
  10 | book | 10
  10 | ball | 10
  </code></pre>