SQL & PL/SQL

This when I created external loader.

Sorry bad English I try to read about this as much, but I really don't see information about.

ORGANIZATION EXTERNAL (

TYPE ORACLE\_LOADER

DEFAULT DIRECTORY DATA\_DIR

ACCESS PARAMETERS (

    RECORDS DELIMITED BY NEWLINE

    FIELDS(

        record\_type POSITION(1:1) char,

        data POSITION(8:256) char,

    )

)

LOCATION ('new\_report\_1m.txt')

) REJECT LIMIT UNLIMITED;

and I want to change those fields by external modify

select * from pma_ext_settlement_report external modify (
ACCESS PARAMETERS (
FIELDS(
record_type POSITION(1:1) char,
data POSITION(8:256) char,
trans_id POSITION(XX:XX) char
)
)
LOCATION ('new_report_1m.txt');
);

But it can't be executed, I don't know if it capable to do this. Thank you so much.