The EMP table has some discrepancy in data entry with a particular employee ID. You
execute the query as shown in the Exhibit to retrieve all versions of the row that exist
between two SCNs.View the Exhibit.
Which two statements about the results of the query shown in the Exhibit are correct?
(Choose two.)
Exhibit:
A.
The LAST_SCN value in the first row is NULL, which means that the versions of the row
still exist at SCN 6636300.
B.
The LAST_SCN value in the second row in NULL, which means that the version of the
row still exists at SCN 6636300.
C.
The LAST_SCN value in the third row is 6636280, which means that the version of row
exists above SCN 6636280.
D.
The LAST_SCN value in the second row is NULL, which means that the version of the
row no longer exists because it was deleted.
Explanation:
Using Oracle Flashback Transaction Query with Oracle Flashback Version Query (link)
The query uses Oracle Flashback Version Query pseudocolumns:
SELECT versions_xid XID, versions_startscn START_SCN,
versions_endscn END_SCN, versions_operation OPERATION,
empname, salary
FROM emp
VERSIONS BETWEEN SCN MINVALUE AND MAXVALUE
WHERE empno = 111;
Results are similar to:3 rows selected.
The results table rows are in descending chronological order.
The third row corresponds to the version of the row in the table emp that was inserted in the
table when the table was created.
The second row corresponds to the row in emp that the erroneous transaction deleted.
The first row corresponds to the version of the row in emp that was reinserted with a new
employee name.
