title: Count NULL Values from multiple columns with SQL
body: <p>I have 3 columns let say <code>A</code>, <code>B</code>, and <code>C</code>. I need to count the <code>NULL</code> values in each column.</p>
  
  <p>For example:</p>
  
  <pre><code> A  | B  | C
  -------------
  1   |NULL| 1
  1   | 1  | NULL
  NULL| 1  | 1
  NULL|NULL| 1
  </code></pre>
  
  <p>Should output:</p>
  
  <pre><code> A  |  B  |  C
  ---------------
   2  |  2  |  1
  </code></pre>
  
  <p>I've tried count, sum, sub-queries but nothing has worked for me yet. Any input would be appreciated!</p>