title: Only display a character if the ISNULL has a valid entry
body: <p>In SQL Server, what I'm looking at doing is concatenating two fields together.  So, for example, I have this layout:</p>
  
  <pre><code>Col1         Col2
  Building A   Room 101
  Building B   Room 2A
  Building C   Room 301
  Building D
  Building E   Room 200
  </code></pre>
  
  <p>And I want to concatenate them like:</p>
  
  <pre><code>Building A-Room 101
  Building B-Room 2A
  Building C-Room 301
  </code></pre>
  
  <p>What is happening when it comes to <code>Building D</code> is I get:</p>
  
  <p><code>Building D-</code></p>
  
  <p>which is awful.  I thought that I could do <code>ISNULL([Col1] + '-', '')</code> but this will always display the <code>-</code> character.  Is there a way to only add the <code>-</code> value if <code>[Col2]</code> has a value without using a <code>CASE</code> statement?  Or am I going about this in the wrong approach?</p>