title: How do I add values of a row based on two unique identifiers
body: <p>I have a table with 3 columns that I am interested in they are Id, Week and Time.
  My select will look like this.</p>
  
  <pre><code>SELECT Id, Week, Time FROM TimeSheet
  </code></pre>
  
  <p>This is the result</p>
  
  <pre><code>+------+------+------+
  | Id   | Week | Time |
  +------+------+------+
  |    1 |    1 | 8.0  |
  |    1 |    1 | 8.0  |
  |    2 |    3 | 8.0  |
  |    2 |    4 | 8.0  |
  |    3 |    5 | 8.0  |
  |    3 |    5 | 3.0  |
  |    3 |    5 | 8.0  |
  |    3 |    5 | 8.0  |
  +------+------+------+
  </code></pre>
  
  <p>The result that I would like is to have it sorted by id and week where time is added together per week so that I can see how much each Id worked per week.
  I really have no idea of how to achieve this, it'm not a developer.</p>
  
  <pre><code>+------+------+------+
  | Id   | Week | Time |
  +------+------+------+
  |    1 |    1 | 16.0 |
  |    2 |    3 |  8.0 |
  |    2 |    4 |  8.0 |
  |    3 |    5 | 27.0 |
  +------+------+------+
  </code></pre>