title: Error converting data type nvarchar to real
body: <p>I need to subtract two nvarchar values and store the result in another column. I understand that first I need to convert nvarchar to numeric values, but I always get this error</p>
  
  <blockquote>
    <p>Error converting data type nvarchar to real</p>
  </blockquote>
  
  <p>Just to mention in varchar values are stored only numeric values but I can't seem to get this conversion right. </p>