title: oracle duplicate rows based on a single column
body: <p>How can I find out duplicate rows based on a single column. I have a table in oracle which has data as given below and it has duplicates. I'm trying to select and view all rows with duplicate employee ids as explained below</p>
  
  <p>EMP table:</p>
  
  <pre><code>EmpId Fname Lname Mname Jobcode Status exp_date
  
  1      Mike Jordan A    IT      W      12/2014
  1      Mike Jordan A    IT      A      12/2014
  2      Angela ruth C    sales   P      12/2015
  2      Angela ruth C    IT      W      12/2015
  3      Kelly  Mike B    sales   W      12/2015
  </code></pre>
  
  <p>From the above table i want to select all rows which duplicate empids such as below</p>
  
  <pre><code>EmpId Fname Lname Mname Jobcode Status exp_date
  
  1      Mike Jordan A    IT      W      12/2014
  1      Mike Jordan A    IT      A      12/2014
  2      Angela ruth C    sales   P      12/2015
  2      Angela ruth C    IT      W      12/2015
  </code></pre>
  
  <p>How can I do this? thank you!</p>