title: PGSQL duplicate record in same column
body: <p>i have a table and i want to know where duplicate records are present for same columns. These are my columns and i want to get record where group_id or week are different for same code and fweek and newcode</p>
  
  <pre><code>Id newcode fweek    code   group_id   week
  1  343001 2016-01   343     100        8
  2  343002 2016-01   343     100        8
  3  343001 2016-01   343     101        08
  </code></pre>
  
  <p>Required record is </p>
  
  <pre><code>Id newcode fweek   code group_id  week
  3  343001  2016-01 343  101       08
  </code></pre>