Section
18 Quiz
(Answer all questions in this
section)
1. 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?
Mark for Review
(1)
Points
78000
30000
24000
48000 (*)
2. 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?
Mark for Review
(1)
Points
A, B, and C
A and B (*)
C
None of the above
3. If Oracle crashes, your changes are
automatically rolled back. True or False?
Mark for Review
(1)
Points
True (*)
False
4. 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?
Mark for Review
(1)
Points
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.
5. COMMIT saves all outstanding data
changes? True or False? Mark for Review
(1)
Points
True (*)
False
6. 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?
Mark for Review
(1)
Points
ROLLBACK to SAVEPOINT Del_Done; (*)
COMMIT Del_Done;
There is nothing you can do.
ROLLBACK UPDATE;
7. 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?
Mark for Review
(1)
Points
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.
8. Which SQL statement is used to remove
all the changes made by an uncommitted transaction? Mark for Review
(1)
Points
REVOKE;
ROLLBACK TO SAVEPOINT;
ROLLBACK; (*)
UNDO;
9. You need not worry about controlling
your transactions. Oracle does it all for you. True or False? Mark for Review
(1)
Points
True
False (*)
10. When
you logout of Oracle, your data changes are automatically rolled back. True or
False? Mark for Review
(1)
Points
True
False (*)
11. 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?
Mark for Review
(1)
Points
22
20 (*)
JANE will receive an error message
because she is not allowed to query the table while BOB is updating it.
2
12. Which
of the following best describes the term "read consistency"? Mark for Review
(1)
Points
It prevents other users from
querying a table while updates are being executed on it
It prevents other users from seeing
changes to a table until those changes have been committed (*)
It prevents users from querying tables
on which they have not been granted SELECT privilege
It ensures that all changes to a
table are automatically committed
13. 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?
Mark for Review
(1)
Points
An object privilege
An update statement
A savepoint (*)
A sequence
A database link
14. If
a database crashes, all uncommitted changes are automatically rolled back. True
or False? Mark for Review
(1)
Points
True (*)
False
15. 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? Mark for Review
(1)
Points
True
False (*)
1. 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?
Mark for Review
(1)
Points
A, B, and C
A and B (*)
C
None of the above
2. 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? Mark
for Review
(1)
Points
True
False (*)
3. 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?
Mark for Review
(1)
Points
JANE will receive an error message
because she is not allowed to query the table while BOB is updating it.
2
20 (*)
22
4. 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?
Mark for Review
(1)
Points
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.
5. 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?
Mark for Review
(1)
Points
24000
30000
48000 (*)
78000
6. When you logout of Oracle, your data
changes are automatically rolled back. True or False? Mark for Review
(1)
Points
True
False (*)
7. Which of the following best describes
the term "read consistency"?
Mark for Review
(1)
Points
It prevents users from querying
tables on which they have not been granted SELECT privilege
It prevents other users from
querying a table while updates are being executed on it
It prevents other users from seeing
changes to a table until those changes have been committed (*)
It ensures that all changes to a
table are automatically committed
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?
Mark for Review
(1)
Points
ROLLBACK UPDATE;
There is nothing you can do.
COMMIT Del_Done;
ROLLBACK to SAVEPOINT Del_Done; (*)
9. If a database crashes, all uncommitted
changes are automatically rolled back. True or False? Mark for Review
(1)
Points
True (*)
False
10. 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?
Mark for Review
(1)
Points
An update statement
A savepoint (*)
A database link
An object privilege
A sequence
11. You
need not worry about controlling your transactions. Oracle does it all for you.
True or False? Mark for Review
(1)
Points
True
False (*)
12. If
Oracle crashes, your changes are automatically rolled back. True or False? Mark for Review
(1)
Points
True (*)
False
13. Which
SQL statement is used to remove all the changes made by an uncommitted
transaction? Mark for Review
(1)
Points
ROLLBACK; (*)
UNDO;
REVOKE;
ROLLBACK TO SAVEPOINT;
14. COMMIT
saves all outstanding data changes? True or False? Mark for Review
(1)
Points
True (*)
False
15. 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?
Mark for Review
(1)
Points
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.
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