title: Self join to show null Mangers in the query result
body: <p>table Employee</p>
  
  <p><code>emp_id   emp_name  emp_manager
  1        Akshay       3
  2        Santosh      3
  3        Naveen       4
  4        Prashanth    5
  5        Punnet       Null</code></p>
  
  <p>fetch all   Mangers associated with employee</p>
  
  <p>query</p>
  
  <p><code>SELECT a.emp_name, b.emp_name AS Manager
  FROM employee AS a
  INNER JOIN employee AS b ON a.emp_manager = b.emp_id</code></p>
  
  <p><code>emp_name   Manager
  Akshay     Naveen
  Santosh    Naveen
  Naveen     Prashanth
  Prashanth  Punnet</code></p>
  
  <p>Null manager is not showing. 
  How to write a query to show Punnet and manager as Null in the query result?</p>