title: DIfference between inline query in select clause and a join in where clause
body: <p>What is the difference between:</p>
  
  <pre><code>select e.first_name,
         e.last_name,
         e.id,
         d.dept_name
  from employees e, departments d
  where e.department_id = d.department_id;
  </code></pre>
  
  <p>and</p>
  
  <pre><code>select e.first_name,
         e.last_name,
         e.id,
         (select d.dept_name frpm departments d where d.department_id = e.department_id) dept_name    
  from employees e;
  </code></pre>
  
  <p>I am talking about differences in performance, query time, CPU utilization etc.
  Which one is better to use?</p>