title: Which is faster comparing an uniqueidentifier or a string in tsql?
body: <p>I have a table which holds the guid for an user and their actual name as a string. I would like to grab some information based on an user. But which field should I use? Should my code say:</p>
  
  <pre><code>select * 
  from userinboxcount 
  where countDate &gt;= startDate and countDate &lt;= endDate and userid = '&lt;guid here&gt;'
  
  or 
  
  select * 
  from userinboxcount 
  where countDate &gt;= startDate and countDate &lt;= endDate and username = "FirstName LastName"
  </code></pre>