title: Why IsNull(LTrim(RTrim(Lower(null))), -1) is *?
body: <p>Today I was testing something at work place and came across this one</p>
  
  <p>Case 1:</p>
  
  <pre><code>Declare @a nvarchar(20)
  Set @a = null
  Select IsNull(LTrim(RTrim(Lower(@a))), -1)
  </code></pre>
  
  <p>Case 2:</p>
  
  <pre><code>Select IsNull(LTrim(RTrim(Lower(null))), -1)
  </code></pre>
  
  <p>The result in case 1 is <code>-1</code> but <code>*</code> in case 2
   I was expecting same results in both cases. Any reason?</p>