External Tables binding to Access?

I only find information connecting Oracle external tables to data
files. But I dont want to transfer data to files instead I want
directly transfer data to oracle from Access. I do not know how to
change the syntax of the below External table binding
>
>
CREATE TABLE city_populations_ext (
city_name VARCHAR(9),
pop_1990 NUMBER,
pop_2000 NUMBER
)
ORGANIZATION EXTERNAL (
TYPE oracle_loader
DEFAULT DIRECTORY census_data
ACCESS PARAMETERS (
RECORDS FIXED 20
LOGFILE census_data:
'city_populations.log'
BADFILE census_data:
'city_populations.bad'
FIELDS
MISSING FIELD VALUES ARE NULL (
city_name (1:10) CHAR(9),
pop_1990 (11:15) INTEGER
EXTERNAL(4),
POP_2000 (16:20) INTEGER
EXTERNAL(4)
)
)
LOCATION ('city_populations.dat')
)
PARALLEL 4 REJECT LIMIT UNLIMITED;