title: SQL query to list the length of service of the employee in the form n years and m months
body: <p>I have a table named employee the columns are </p>
  
  <pre><code>empid,empname,joining date,retiring date  
  1,employee,2000-1-1,2010-3-1
  </code></pre>
  
  <p>I have to fetch the length of service of the employee. The output should be as follows:</p>
  
  <pre><code>years  months
  10      2
  </code></pre>