title: Identifying identical pairs across two tables
body: <p>I have two tables that has the same data. It is collected over two weeks. For example</p>
  
  <p>In table 1 you have </p>
  
  <pre><code>IP|Zip|state
  x.x.x.x|abcde|NJ
  y.y.y.y|qwert|NY
  z.z.z.z|werty|NH
  </code></pre>
  
  <p>In table 2 you have</p>
  
  <pre><code>IP|Zip|state
  x.x.x.x|abcde|NJ
  y.y.y.y|qwert|NY
  m.m.m.m|werty|NH
  z.z.z.z|merty|CA
  </code></pre>
  
  <p>I am looking to overlap these tables and compare of IP:Zip pairs and then count number of IPs changed zip by state of table 1. Thanks for the help!</p>