title: If column data is null or contains an empty string then 'N/A'
body: <p>I have a column called County, and in this column sometimes there is a county and other times its either empty or contains NULL. So far I am able to change it when there is an empty string to N/A, but not sure how to change it if there is a NULL as well.
  So far I am using a case statement to check if the column contains an empty string</p>
  
  <pre><code>case County when '' then 'N/A' end
  </code></pre>
  
  <p>but I need to check if the column data is NULL as well and change it to N/A.</p>
  
  <p>So in short, if any data in the County column is an empty string or is NULL then I need to add N/A.</p>