title: how to sum the rows of this table consistently with the id in sql?
body: <p>I have this table which stores all the game tuples within a chess tournament.
  The IDs of the black player and the white player are referenced to another table called 'players', where the id is unique.</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>game_id</th>
  <th>id_white_player</th>
  <th>id_black_player</th>
  <th>white_points</th>
  <th>black_points</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>1</td>
  <td>38</td>
  <td>91</td>
  <td>1</td>
  <td>0</td>
  </tr>
  <tr>
  <td>2</td>
  <td>41</td>
  <td>38</td>
  <td>0</td>
  <td>1</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>In my failed attempts I have tried to achieve something like this:</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>player_id</th>
  <th>points_sum</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>38</td>
  <td>2</td>
  </tr>
  <tr>
  <td>91</td>
  <td>0</td>
  </tr>
  <tr>
  <td>41</td>
  <td>0</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>So I need a table that sums up both the points of the games played as 'black' and those played as 'white'.</p>
  <p>I'm not sure how I can do this in sql (currently working on PostgreSQL). Thank you in advance!</p>