odbc::get-cast-binary

  Hello.
  I've noticed that there's a problem with odbc::get-cast-binary. When
SELECTing a column of type TIMESTAMP from MSSQL database, an error is
signalled sometimes telling that a negative number is not
unsigned-byte. I don't have any FFI experience yet, but I've
noticed that it's possible to fix the problem by replacing :byte with
:unsigned-byte
in the (with-cast-pointer ...) form, see below:

(defun get-cast-binary (ptr len format)
  "FORMAT is one of :unsigned-byte-vector, :bit-vector (:string, :hex-string)"
  (with-cast-pointer (casted ptr :byte) ; <--- SHOULD BE :unsigned-byte
     ....

This seems to help, but I'm not 100% sure...

  Thanks,
    Ivan