title: Compare columns in a table and only show differences
body: <p>I have two columns in the same table that I'm trying to compare. The issue is that they don't have to be identical to be considered "the same". Below I'll try to explain with an example.</p>
  
  <p>Example:</p>
  
  <pre><code>HOST_NAME     ENVIRONMENT                  SUBNET_ENVIRONMENT
  host1         Production                   Prod
  host2         Development(Dev)/Testing     Non-Prod
  host3         Development(Dev)             Prod
  host4         Production                   Non-Prod
  host5         Testing/UAT                  Prod
  host6         DR                           Prod
  </code></pre>
  
  <p>Essentially, if the "SUBNET_ENVIRONMENT" is Prod, the ENVIRONMENT should be "Production" as well. If the "SUBNET_ENVIRONMENT" is Non-Prod, the ENVIRONMENT should be anything besides "Production". </p>
  
  <p>In this example, the first two would (host1 and host2) would be considered correct, and therefore be left out of the results. The following 4 (host{3-6}) are "different" so these are the ones that I want to be shown in the results of the query.</p>
  
  <p>Below is a sample query for how I get the entire resultset. How can I modify this to only show the differences?</p>
  
  <pre><code>SELECT
     HOST_NAME,
     REPLACE(HOST_ENVIRONMENT,',','/') HOST_ENV,
     HOST_SUBNET_ENV
  FROM 
     HOST_TABLE
  </code></pre>