title: Why can't I put a constraint on nvarchar(max)?
body: <p>Why can't I create a constraint on an <code>nvarchar(max)</code> column? SQL Server will not allow me to put a unique constraint on it. But, it allows me to create a unique constraint on an <code>nvarchar(100)</code> column.</p>
  
  <p>Both of these columns are <code>NOT NULL</code>. Is there any reason I can't add a constraint to the <code>nvarchar(max)</code> column?</p>