The standard does not permit this data type conversion

  Explanation:  You are comparing, assigning or unioning to
  expressions with different data types.  These two expressions
  must be converted to a common data type.  The ANSI and ISO SQL
  standards do not support this conversion.

  User Action:  If it is important to have only standard features
  in your program, you should change your statement to use
  supported conversions.