title: Sql aggregate function to obtain a list
body: <p>Hei!</p>
  
  <p>How can I create an aggregate function to obtain a list of the aggregate values.</p>
  
  <p>given : </p>
  
  <pre><code>key     value
  Andrei  1
  Andrei  2
  Andrei  3
  Mihai   4
  Mihai   5
  Mihai   6
  </code></pre>
  
  <p>I want</p>
  
  <pre><code>key list
  Andrei 1,2,3
  Mihai 4,5,6
  </code></pre>