Determine if row has ever been updated - sql

Question

Might be a long shot, but I'm looking for a way to see if a row has ever been updated since it was inserted.
Ex.
CREATE TABLE TEST_DATA AS
( SELECT 'A' AS dummy
FROM dual
UNION
SELECT 'B' AS dummy
FROM dual
);
UPDATE TEST_DATA
SET dummy = 'C'
WHERE dummy = 'B';
Is there any way I can tell that the 'C' record has been updated?
Also, I have absolutely no control over the data model so I can't add an add timestamp and an update timestamp to the actual table.

Answer 1

this will work:
create table test_data(a varchar(1));
insert into test_data values('A');
insert into test_data values('B');
insert into test_data values('C');
insert into test_data values('D');
select * from test_data;
A
B
C
D
create table noofchanges(data varchar(1),numberofchanges int) ;
insert into noofchanges(data,numberofchanges) select a,0 from test_data;
select * from noofchanges;
A 0
B 0
C 0
D 0
CREATE OR REPLACE TRIGGER test_data_before_update
BEFORE UPDATE
ON test_data
FOR EACH ROW
BEGIN
update noofchanges
set numberofchanges=numberofchanges+1
where data=:old.a;
END;
update test_data set a='A' where a='B';
select * from test_data;
A
A
C
D
select * from noofchanges
A 0
B 1
C 0
D 0
thank you!!!!!!