SOLOSOLOKU: Section 18 Quiz

Test: Section 18 Quiz
Review your answers, feedback, and question scores below. An asterisk (*) indicates a correct answer.

Section 18 Quiz
(Answer all questions in this section)

1. Examine the following statements:
UPDATE employees SET salary = 15000;
SAVEPOINT upd1_done;
UPDATE employees SET salary = 22000;
SAVEPOINT upd2_done;
DELETE FROM employees;

You want to retain all the employees with a salary of 15000; What statement would you execute next?
ROLLBACK;
ROLLBACK TO SAVEPOINT upd1_done; (*)
ROLLBACK TO SAVEPOINT upd2_done;
ROLLBACK TO SAVE upd1_done;
There is nothing you can do; either all changes must be rolled back, or none of them can be rolled back.

2. Which SQL statement is used to remove all the changes made by an uncommitted transaction?
ROLLBACK; (*)
REVOKE;
UNDO;
ROLLBACK TO SAVEPOINT;

3. When you logout of Oracle, your data changes are automatically rolled back. True or False?
True
False (*)

4. If Oracle crashes, your changes are automatically rolled back. True or False?
True (*)
False

5. If UserB has privileges to see the data in a table, as soon as UserA has entered data into that table, UserB can see that data. True or False?
True
False (*)

Test: Section 18 Quiz
Review your answers, feedback, and question scores below. An asterisk (*) indicates a correct answer.

Section 18 Quiz
(Answer all questions in this section)

6. User BOB's CUSTOMERS table contains 20 rows. BOB inserts two more rows into the table but does not COMMIT his changes. User JANE now executes:
SELECT COUNT(*) FROM bob.customers;
What result will JANE see?
2
JANE will receive an error message because she is not allowed to query the table while BOB is updating it.
20 (*)
22

7. A transaction makes several successive changes to a table. If required, you want to be able to rollback the later changes while keeping the earlier changes. What must you include in your code to do this?
A database link
A sequence
An object privilege
A savepoint (*)
An update statement

8. Examine the following statements:
INSERT INTO emps SELECT * FROM employees; -- 107 rows inserted.
SAVEPOINT Ins_Done;
DELETE employees; -- 107 rows deleted
SAVEPOINT Del_Done;
UPDATE emps SET last_name = 'Smith';

How would you undo the last Update only?
There is nothing you can do.
COMMIT Del_Done;
ROLLBACK to SAVEPOINT Del_Done; (*)
ROLLBACK UPDATE;

9. Table MYTAB contains only one column of datatype CHAR(1). A user executes the
following statements in the order shown.
INSERT INTO mytab VALUES ('A');
INSERT INTO mytab VALUES ('B');
COMMIT;
INSERT INTO mytab VALUES ('C');
ROLLBACK;

Which rows does the table now contain?
A, B, and C
A and B (*)
C
None of the above

10. You need not worry about controlling your transactions. Oracle does it all for you. True or False?
True
False (*)

Test: Section 18 Quiz
Review your answers, feedback, and question scores below. An asterisk (*) indicates a correct answer.

Section 18 Quiz
(Answer all questions in this section)

11. Examine the following statements:
INSERT INTO emps SELECT * FROM employees; -- 107 rows inserted.
SAVEPOINT Ins_Done;
CREATE INDEX emp_lname_idx ON employees(last_name);
UPDATE emps SET last_name = 'Smith';

What happens if you issue a Rollback statement?
The update of last_name is undone, but the insert was committed by the CREATE INDEX statement. (*)
Both the UPDATE and the INSERT will be rolled back.
The INSERT is undone but the UPDATE is committed.
Nothing happens.

12. COMMIT saves all outstanding data changes? True or False?
True (*)
False

13. Which of the following best describes the term "read consistency"?
It ensures that all changes to a table are automatically committed
It prevents users from querying tables on which they have not been granted SELECT privilege
It prevents other users from seeing changes to a table until those changes have been committed (*)
It prevents other users from querying a table while updates are being executed on it

14. If a database crashes, all uncommitted changes are automatically rolled back. True or False?
True (*)
False

15. Steven King's row in the EMPLOYEES table has EMPLOYEE_ID = 100 and SALARY = 24000. A user issues the following statements in the order shown:
UPDATE employees
SET salary = salary * 2
WHERE employee_id = 100;
COMMIT;

UPDATE employees
SET salary = 30000
WHERE employee_id = 100;

The user's database session now ends abnormally. What is now King's salary in the table?
78000
30000
48000 (*)
24000