title: Merge multiple rows having some identity to a new one that have the sum of a column thats is distinct between thems
body: <p>I have table like this :</p>
  
  <pre><code>id    name    qt
  ----------------
   0      mm     4
   1      mm     5
   2      xx     8
  </code></pre>
  
  <p>I want update it or get new table that will produce this kind of result:</p>
  
  <pre><code>id   name     qt
  ------------------
   0     mm      9 (sum of the two or multiple some identical )
   1     xx      8
  </code></pre>