SQL> create or replace Directory dir121 as '/ren/oracle';
Directory created.
SQL>DECLARE
 V_LOB CLOB;
 V_FILE BFILE := BFILENAME('DIR121', 'value.txt');
 V_SOURCE NUMBER := 1;
 V_DEST NUMBER := 1;
 V_LANG NUMBER := 0;
 V_WARN NUMBER;
 BEGIN
 UPDATE CU SET VALUE = EMPTY_CLOB WHERE ID='5' RETURN VALUE INTO V_LOB;
 DBMS_LOB.FILEOPEN(V_FILE);
 DBMS_LOB.OPEN(V_LOB, DBMS_LOB.LOB_READWRITE);
 DBMS_LOB.LOADCLOBFROMFILE(V_LOB,
 V_FILE,
 DBMS_LOB.LOBMAXSIZE,
 V_DEST,
 V_SOURCE,
 0,
 V_LANG,
 V_WARN);
 DBMS_LOB.CLOSE(V_LOB);
 DBMS_LOB.FILECLOSEALL;
 COMMIT;
 END;
 /