title: Coalesce for zero instead of null
body: <p>I have a simple company table which inconsistently use column name <code>turnover</code> and <code>revenue</code>. The table currently looks like this:</p>
  
  <pre><code>company, turnover, revenue
  A, 10000, 0
  B, 0, 2500
  C, 0, 3000
  4, 23000, 0
  </code></pre>
  
  <p>I know how to use coalesce to choose between null and value, but there the value to be discarded is zero instead of null.</p>
  
  <p>The end result that I want is:</p>
  
  <pre><code>company, revenue
  A, 10000
  B, 2500
  C, 3000
  D, 23000
  </code></pre>
  
  <p>The query that I'm imagining is:</p>
  
  <pre><code>select company, coalesce_for_zero(turnover, revenue) as revenue from
  company_profile;
  </code></pre>
  
  <p>How do I write a query that can achieve coalesce-like results for zero?</p>