title: Concatenate grouped rows
body: <p>I would like to know is it possible from this table</p>
  
  <pre><code>ID   Price    ServiceID
  1    50       11
  1    -10      12
  2    100      11
  2    20       11
  </code></pre>
  
  <p>to group by ID, sum the price and concatenate serviceID, something like this:</p>
  
  <pre><code>ID   Price    ServiceID
  1    40       11,12
  2    120      11
  </code></pre>
  
  <p>It is rather simple to group by ID and sum the price, but concatenate service IDs what is troubling me.</p>
  
  <p>Thank you for participating.</p>