title: Replacing NULL and empty string within Select statement
body: <p>I have a column that can have either <code>NULL</code> or empty space (i.e. <code>''</code>) values.  I would like to replace both of those values with a valid value like <code>'UNKNOWN'</code>.  The various solutions I have found suggest modifying the value within the table itself.  However, this is not an option in this case in that the database is for a 3rd party application that is developed and/or patched very poorly (in reality I think my Rottweiler could have done a better job).  I am concerned that modifying the underlying data could cause the application to melt into a smoking hole.</p>
  
  <p>I have attempted variations of the following commands:</p>
  
  <pre><code>COALESCE(Address.COUNTRY, 'United States') -- Won't replace empty string as it is not NULL
  REPLACE(Address.COUNTRY, '', 'United States') -- Doesn't replace empty string
  ISNULL(Address.COUNTRY, 'United States') -- Works for NULL but not empty string
  </code></pre>
  
  <p>I know I could use the <code>CASE</code> statement but am <em>hoping</em> there is a much more elegant/efficient solution.</p>
  
  <p>You'll have to trust me when I say I have looked for a solution to my specific issue and have not found an answer.  If I have overlooked something, though, kindly show me the lighted path.</p>