title: cast decimal value to NULL if value is 0.000000
body: <p>I would like to handle the decimal values 0.000000 and NULL in null-able column both as NULL</p>
  
  <p>For example:</p>
  
  <pre><code>case worthColumn
  WHEN '0.000000' then NULL
  WHEN NULL then NULL
  ELSE worthColumn
  END 
  AS SumOfWorth
  </code></pre>
  
  <p>But the value 0.000000 always ends up in the result ?</p>