title: Unicode issue in sql server, some characters cannot be saved in a varchar field
body: <p>I'm dealing with unicode stuff in my DB. I have a data field defined as varchar(max),
  and I'm preventing user to save unknown characters in this field, like "≤" for example (all unicode above U+00FF).
  While doing so, I found that some characters if sent to be saved in this field would be displayed as "?", so I thought that all unicode characters above "U+00FF" will all be displayed like this, but then I found that "U+201B" which is "‛" is displayed "?" but the next character "U+201C" which is "“" is displayed as "“". 
  Can someone please explain to me why is that?</p>
  
  <p>Update: Sorry if I was not clear, but I do not want to convert to nvarchar, I want to keep my field as varchar. 
  What I need to understand is why a character like "‛" is displayed as "?" in a "varchar" field while the next unicode character "“" is displayed properly? </p>