create table ext_table_csv (
  i   Number,
  n   Varchar2(20)
)
organization external (
  type              oracle_loader
  default directory ext_dir
  access parameters (
    records delimited  by newline
    BADFILE 'D:\wence\External_tables\test.bad'
    LOGFILE 'D:\wence\External_tables\test.log'
    fields  terminated by ','
    missing field values are null
  )
  location ('D:\wence\External_tables\test.csv')
)
reject limit unlimited;

select *
from ext_table_csv

ORA-29913: error in executing ODCIEXTTABLEOPEN callout
ORA-29400: data cartridge error
KUP-00554: error encountered while parsing access parameters
KUP-01006: error signalled during parse of access parameters
KUP-00562: unknown escape sequence
ORA-06512: at "SYS.ORACLE_LOADER", line 19

CREATE OR REPLACE DIRECTORY ext_dir AS 'D:\wence\External_tables';

GRANT READ ON DIRECTORY ext_dir TO public;

GRANT WRITE ON DIRECTORY ext_dir TO public;


create table ext_table_csv (
  i   Number,
  n   Varchar2(20)
)
organization external (
  type              oracle_loader
  default directory ext_dir
  access parameters (
    records delimited  by newline
    BADFILE 'test.bad'
    LOGFILE 'test.log'
    fields  terminated by ','
    missing field values are null
  )
  location ('test.csv')
)
reject limit unlimited;

SQL> edit
Wrote file afiedt.buf

  1  SELECT TABLE_NAME, DEFAULT_DIRECTORY_OWNER, DEFAULT_DIRECTORY_NAME
  2* FROM USER_EXTERNAL_TABLES
SQL> /

TABLE_NAME                     DEF DEFAULT_DIRECTORY_NAME
------------------------------ --- ------------------------------
EXT_TABLE_CSV                  SYS EXT_DIR