title: Select first row in each GROUP BY group
body: <p>I have a requirement in my project that I have this data with me:</p>
  
  <pre><code>C1 | C2 | C3 | C4
  A  | B  | 2  | X
  A  | B  | 3  | Y
  C  | D  | 4  | Q
  C  | D  | 1  | P
  </code></pre>
  
  <p>Where C1, C2, C3 and C4 are columns name in Database</p>
  
  <p>And I have need to show data like this</p>
  
  <pre><code>C1 | C2 | C3 | C4
  A  | B  | 5  | X
  C  | D  | 5  | Q
  </code></pre>