title: SQL Server unique constraint problem
body: <p>How to create a unique constraint on a varchar(max) field in visual studio, visually.</p>
  
  <p>the problem is when i try it:</p>
  
  <p><strong>manage indexes and keys > add > columns</strong></p>
  
  <p>I can only chose the bigint columns, but not any of the varchar(max) ones.</p>
  
  <p>Do I maybe have to use <strong>check constraints</strong>?</p>
  
  <p>If yes, what to put in the expression?</p>
  
  <p>Thnx for the info</p>