title: MYSQL show 0 even if results do not exist
body: <p>I have a MySql database with 2 tables:</p>
  
  <pre><code>countries
  results
  </code></pre>
  
  <ul>
  <li>Countries is just and <code>id</code> and a <code>country name</code>.</li>
  <li>Results is a <code>country_id</code>, a <code>value</code> and a <code>date</code>.</li>
  <li>Not all countries have results on each date.</li>
  </ul>
  
  <p>How can I create a query that lists all countries with their specific result, but still list them and shows 0 if there is no result on the results table?</p>