title: SQL server: Addition based on multiple columns
body: <p>I have a table of order information called Demands with data that would look something like this:</p>
  
  <pre><code>Invoice | Product | Quantity | Route
  ————————|—————————|——————————|——————————
  2254619 | A       | 10       | 20160112
  2254619 | B       | 5        | 20160112
  2254619 | C       | 4        | 20160112
  2254619 | D       | 7        | 20160112
  2254619 | E       | 3        | 20160112
  2254808 | A       | 8        | 20160112
  2254808 | B       | 2        | 20160112
  2254808 | C       | 9        | 20160112
  2254808 | D       | 0        | 20160112
  2254808 | E       | 11       | 20160112
  2254902 | A       | 7        | 20160113
  2254905 | A       | 4        | 20160113
  </code></pre>
  
  <p>What I need is a query that will calculate the total <strong>Quantity</strong> for ALL <strong>Products</strong> for every <strong>Route</strong>.<p></p>
  
  <p>So, the results would show that Route 20160112 has a Quantity of 18 of Product A, 7 of Product B, etc. and that Route 20160113 has 11 Product A, etc.</p>
  
  <p>And this will be for multiple routes and many different products.<p></p>
  
  <p>Any help you guys can provide would be immensely appreciated.</p>