title: What is the difference between oracle's 'yy' and 'rr' date mask?
body: <p>Example:</p>
  
  <pre><code>select ename from emp where hiredate = todate('01/05/81','dd/mm/yy')
  </code></pre>
  
  <p>and </p>
  
  <pre><code>select ename from emp where hiredate = todate('01/05/81','dd/mm/rr')
  </code></pre>
  
  <p>return different results</p>