title: (NOT) NULL for NVARCHAR columns
body: <p>Allowing <code>NULL</code> values on a column is normally done to allow the absense of a value to be represented. When using <code>NVARCHAR</code> there is aldready a possibility to have an empty string, without setting the column to <code>NULL</code>. In most cases I cannot see a semantical difference between an <code>NVARCHAR</code> with an empty string and a <code>NULL</code> value for such a column.</p>
  
  <p>Setting the column as <code>NOT NULL</code> saves me from having to deal with the possibility of <code>NULL</code> values in the code and it feels better to not have to different representations of "no value" (<code>NULL</code> or an empty string).</p>
  
  <p>Will I run into any other problems by setting my <code>NVARCHAR</code> columns to <code>NOT NULL</code>. Performance? Storage size? Anything I've overlooked on the usage of the values in the client code?</p>