title: "Operand data type nvarchar is invalid for minus operator" in SSRS query designer/refresh fields
body: <p>I have a valid query (tested in SSMS and also running fine in report Preview) however it will not update the dataset with the fields.</p>
  
  <p>How can I force it to do so without manually entering all the fields?</p>
  
  <p>Currently, if I click "Refresh Fields" I get the above error returned</p>