title: How do I use SELECT GROUP BY in DataTable.Select(Expression)?
body: <p>I try to remove the duplicate rows by select a first row from every group.
  For Example</p>
  
  <pre><code>PK     Col1     Col2
  1        A        B
  2        A        B
  3        C        C
  4        C        C
  </code></pre>
  
  <p>I want a return:</p>
  
  <pre><code>PK     Col1     Col2
  1        A        B
  3        C        C
  </code></pre>
  
  <p>I tried following code but it didn't work:</p>
  
  <pre><code>DataTable dt = GetSampleDataTable(); //Get the table above.
  dt = dt.Select("SELECT MIN(PK), Col1, Col2 GROUP BY Col1, Col2);
  </code></pre>