title: Find rows where related row is the same
body: <p>I want to find rows in part id, i.e column name <code>PID</code> where the supplier id i.e <code>S_ID</code> is same for that part id.</p>
  
  <pre><code>+----+-----+
  |PID | SID |
  +----+-----+
  | 11 |  31 |
  | 12 |  35 |
  | 11 |  32 |
  | 11 |  35 |
  | 13 |  34 |
  +----+-----+
  </code></pre>
  
  <p>I am expecting the result as following:</p>
  
  <pre><code>+----+-----+
  |PID | SID |
  +----+-----+
  | 11 |  31 |
  | 11 |  32 |
  | 11 |  35 |
  +----+-----+
  </code></pre>
  
  <p>I tried running the query as following but getting an empty table.</p>
  
  <pre><code>SELECT S_ID FROM P_CATALOG
  GROUP BY PID, S_ID
  HAVING COUNT(S_ID)&gt;1
  </code></pre>
  
  <p>What should I do?</p>