title: Select all rows having duplicate phone numbers with different zone codes?
body: <p>I have a table called <code>contacts</code> with following fields:</p>
  
  <pre><code>+----+-------+--------------+
  | id | name  | phone_no     |
  +----+-------+--------------+
  </code></pre>
  
  <p>Suppose, I have have following values in this table : </p>
  
  <pre><code>+----+-------+--------------+
  | id | name  | phone_no     |
  +----+-------+--------------+
  | 1  | Alex  | 9907661234   |--1, 2 are 
  | 2  | Alex  | 09907661234  |--Same contacts but preceding with '0'
  | 3  | John  | 9879612363   |--Same contacts but preceding with '91'
  | 4  | John  | 919879612363 |-- 91 is (country code)
  | 5  | Shawn | 9979867123   |
  +----+-------+--------------+
  </code></pre>
  
  <p>I want to find number of duplicate contacts with duplicate numbers (here numbers preceded) with <code>0</code> and <code>91</code> are duplicates.</p>
  
  <p>I want following output : </p>
  
  <pre><code>+------------+-------------+
  | phone_no   |     cn      |
  +------------+-------------+
  | 9879612363 |           2 |
  | 9907661234 |           2 |
  +------------+-------------+
  </code></pre>