title: SQL Join with logical operators
body: <p>Data structure and example:</p>
  
  <pre><code>Employees
  id  name
  1   Mike Jensen
  2   Lisa Miller
  
  Skills
  eid name
  1   SQL
  1   PHP
  </code></pre>
  
  <p>Query for Employees with Skills SQL or PHP:</p>
  
  <pre><code>SELECT * FROM Employees LEFT JOIN Skills ON (Employees.id = Skills.eid) WHERE Skills.name = "SQL" OR Skills.name = "PHP" GROUP BY Employees.id
  </code></pre>
  
  <p>Query for Employees with Skills SQL and PHP:</p>
  
  <pre><code>SELECT * FROM Employees LEFT JOIN Skills ON (Employees.id = Skills.eid) WHERE Skills.name = "SQL" OR Skills.name = "PHP" GROUP BY Employees.id HAVING COUNT(*) = 2
  </code></pre>
  
  <p>But what would the query look like for Employees with Skills PHP and (SQL or JS)?</p>