title: How can I use group, inner join and sum?
body: <p>I have two Tables: <strong>Products</strong> &amp; <strong>Sales</strong>.</p>
  
  <p><strong>Products</strong></p>
  
  <pre><code>id- productname  -  grp
  
  11    bmwblue       bmw
  12    bmwwhite      bmw
  13    audiblack     audi
  14    audiwhite     audi
  </code></pre>
  
  <p><strong>Sales</strong></p>
  
  <pre><code> id   productid  amount
  
   1      11        2
   2      12        1
   x      13        5
   x      14        3
  </code></pre>
  
  <p>How can I show;</p>
  
  <p>audi 8, bmw 3 ?</p>