title: Why does this give `error converting data type varchar to numeric`
body: <p>I am having a SQL issue, and I have boiled it down to this:</p>
  
  <pre><code>if isnull(5.5,'') = isnull(null,'') select 0 else select 1
  </code></pre>
  
  <p>which throws the error <code>Error Converting data type varchar to numeric.</code></p>
  
  <p>Why is this throwing this error, and how to resolve?</p>