title: How to see if columns contain nulls and count them if they have in SQL
body: <pre><code>SELECT 
      COUNT(1) - COUNT(NAME) as Name,
      COUNT(1) - COUNT(SURNAME) as Surname,
      COUNT(1) - COUNT(AGE) as Age 
  FROM
      Employees
  </code></pre>
  <p>That's my code to count the number of nulls the columns have. But I want to count only columns which have nulls. How do I do that?</p>