title: SQL query one to many relationship
body: <p>I have a table for Employees and another table with
  Training. The training table contains various training classes that the
  employees have completed. We have mandatory security awareness training, so
  every employee must complete this training class. I’m having trouble running a query that will return ALL employees' either listed completing the training or not.</p>
  
  <p>Example Employee table</p>
  
  <pre><code>╔════╦══════╗
  ║ ID ║ NAME ║
  ╠════╬══════╣
  ║  1 ║ Bob  ║
  ║  2 ║ Tom  ║
  ║  3 ║ John ║
  ╚════╩══════╩
  </code></pre>
  
  <p>Example Training table</p>
  
  <pre><code>╔════╦══════════════╦════════════════════╗
  ║ ID ║ DEPARTMENT_ID║       CLASS        ║
  ╠════╬══════════════╬════════════════════╣
  ║  1 ║           1  ║ Security Awareness ║
  ║  2 ║           1  ║ Workplace Safety   ║
  ║  3 ║           2  ║ Security Awareness ║
  ╚════╩══════════════╩════════════════════╝
  </code></pre>
  
  <p>Target result</p>
  
  <pre><code>╔════╦══════╦════════════════════╗
  ║ ID ║ NAME ║       CLASS        ║
  ╠════╬══════╬════════════════════╣
  ║  1 ║ Bob  ║ Security Awareness ║
  ║  2 ║ Tom  ║ Security Awareness ║
  ║  3 ║ John ║ (null)             ║
  ╚════╩══════╩════════════════════╝
  </code></pre>
  
  <p>The query that I am using is </p>
  
  <pre><code>SELECT employee.id, employee.name, training.class
  FROM employee
  JOIN training ON employee.id = training.department_id
  WHERE training.class LIKE '%SECURITY%'
  ORDER BY employee_id
  </code></pre>
  
  <p>The employee missing the "Security Awareness" class just don't appear, and falls through the cracks.</p>