title: How to use JOIN in mysql to show all data which are not matching
body: <p>I want to show data from 2 tables and I want to show them all including data that are not matching. I've tried with this query.</p>
  
  <pre><code>SELECT * FROM student s
  LEFT JOIN grade g ON g.student_id=s.student_id
  WHERE s.student_id = 9
  </code></pre>
  
  <p>What I get is only showing students who have grade while what I need is showing all students even if they don't have any grade. I also tried using <code>inner join</code>, <code>right join</code> but the result is just the same. What should the query be?</p>