title: How to match the values of two columns(same table) in diagonal and display the result when they don't match
body: <p>I have a <code>city</code> table that has two columns </p>
  
  <pre><code>from_city
  to_city 
  </code></pre>
  
  <p>now lets assume that one row has the following values </p>
  
  <pre><code>'lahore'
  'peshawar' 
  </code></pre>
  
  <p>and the next row has </p>
  
  <pre><code>'peshawar'
  'lahore'
  </code></pre>
  
  <p>Notice that the values match diagonally. I want to display all the rows that don't match in such a manner. </p>
  
  <p>Any help will be much appreciated.</p>