ok, I know it's monday, but I'm sure I'm awake...!

Just wondered why I'm getting this result:

1 select table_name, cache from dba_tables
2* where cache != 'N'
SQL> /

TABLE_NAME CACHE
------------------------------ -----
CDEF$ N
TAB$ N
IND$ N
CLU$ N
USER$ N

etc. for all tables.

but:

1 select table_name, cache from dba_tables
2* where cache = 'N'
SQL> /

no rows selected

I have no tables cached - I know that, so I guess I must've made the most basic error in my query?!