When you use librefs that refer to DBMS data with SAS
functions, some functions might return a value that differs from what
is returned when you use the functions with normal SAS data sets.
For example, the PATHNAME function might return a blank value. For
a normal SAS libref, a blank value means that the libref is not valid.
However, for a libref associated with a DBMS object, a blank value
means only that there is no pathname associated with the libref.
Usage of some functions
might also vary. For example, the LIBNAME function can accept an optional SAS-library
When you use the LIBNAME function to assign or unassign a libref that
refers to DBMS data, you omit this argument. For full details about
how to use SAS functions, see the SAS Functions and CALL Routines: Reference