What must be the value in the ADVT_SOURCE column for the above code to execute successfully?

I think, D is correct…

I’ve executed this code and it works as it is, and when “lobloc CLOB := empty_clob();”

hi no, D is wrong

it may be B and C

it’s also true that non null values ( C ) include also an empty locator (B)
how could we answer so ? C or C and B ?

this is the demonstratio that D is wrong and B s right…

create table print_media
(
ADVT_ID NUMBER,
ADVT_SOURCE CLOB
);

insert into print_media values (1, null);

insert into print_media values (2, null);

Examine the following PL/SQL block:

DECLARE
lobloc CLOB;
buffer VARCHAR2(100);
amount NUMBER;
offset NUMBER := 1;
BEGIN
buffer := ‘This is the second line of a new document’;
amount := LENGTH(buffer);
SELECT advt_source INTO lobloc FROM print_media WHERE advt_id=2 FOR UPDATE;
DBMS_LOB.WRITE(lobloc,amount,offset,buffer);
COMMIT;
END;

ORA-06502: PL/SQL: errore : invalid LOB locator specified: ORA-22275 di numero o valore
ORA-06512: a “SYS.DBMS_LOB”, line 1132
ORA-06512: a line 10

truncate table print_media

insert into print_media values (1, empty_clob());

insert into print_media values (2, empty_clob());

DECLARE
lobloc CLOB;
buffer VARCHAR2(100);
amount NUMBER;
offset NUMBER := 1;
BEGIN
buffer := ‘This is the second line of a new document’;
amount := LENGTH(buffer);
SELECT advt_source INTO lobloc FROM print_media WHERE advt_id=2 FOR UPDATE;
DBMS_LOB.WRITE(lobloc,amount,offset,buffer);
COMMIT;
END;

select * from print_media

2 This is the second line of a new document