PLSQL Mid Term Exam Semester 1 - Part II

1. For which type of SQL statement must you use an explicit cursor?
DML statements that process more than one row.
Queries that return more than one row. (*)
Data Definition Language (DDL) statements.
Queries that return a single row.

2. After a cursor has been closed, it can be opened again in the same PL/SQL block. True or False?
True (*)
False

3. Which of these is NOT a valid cursor declaration?
CURSOR emp_curs IS
SELECT salary
FROM employees
ORDER BY salary DESC;

CURSOR emp_curs IS
SELECT salary
FROM employees
WHERE last_name LIKE 'S%';

CURSOR emp_dept_curs IS
SELECT e.salary, d.department_name
FROM employees e, departments d
WHERE e.department_id = d.department_id;

CURSOR emp_curs IS
SELECT salary INTO v_salary
FROM employees; (*)

4. Which of these constructs can be used to fetch multiple rows from a cursor's active set?
A CASE statement
An IF .... ELSE statement
A basic loop which includes FETCH and EXIT WHEN statements (*)
A basic loop which includes OPEN, FETCH and CLOSE statements

5. The employees table contains 20 rows. What will happen when the following code is executed?
DECLARE
&nbspCURSOR emp_curs IS
&nbspSELECT job_id FROM employees;
v_job_id employees.job_id%TYPE;
BEGIN
OPEN emp_curs;
LOOP
FETCH emp_curs INTO v_job_id;
DBMS_OUTPUT.PUT_LINE(v_job_id);
EXIT WHEN emp_curs%NOTFOUND;
END LOOP;
CLOSE emp_curs;
END;

20 job_ids will be displayed.
The block will fail and an error message will be displayed.
21 rows of output will be displayed; the first job_id will be displayed twice.
21 rows of output will be displayed; the last job_id will be displayed twice. (*)

6. Which of these statements about implicit cursors is NOT true?
They are declared automatically by Oracle for single-row SELECT statements.
They are declared automatically by Oracle for all DML statements.
They are declared by the PL/SQL programmer. (*)
They are opened and closed automatically by Oracle.

7. What will happen when the following code is executed?
DECLARE
CURSOR emp_curs IS
SELECT salary FROM employees;
v_salary employees.salary%TYPE;
BEGIN
FETCH emp_curs INTO v_salary;
DBMS_OUTPUT.PUT_LINE(v_salary);
CLOSE emp_curs;
END;

The first employee's salary will be fetched and displayed.
All employees' salaries will be fetched and displayed.
The execution will fail and an error message will be displayed. (*)
The lowest salary value will be fetched and displayed.

8. What will happen when the following code is executed?
DECLARE CURSOR emp_curs IS
SELECT salary FROM employees;
v_salary employees.salary%TYPE;
BEGIN
OPEN emp_curs;
FETCH emp_curs INTO v_salary;
CLOSE emp_curs;
FETCH emp_curs INTO v_salary;
END;

The block will fail and an INVALID_CURSOR exception will be raised. (*)
The first employee row will be fetched twice.
The first two employee rows will be fetched.
The block will fail and a TOO_MANY_ROWS exception will be raised.

9. In the following code fragment, you want to exit from the outer loop at Line A if  v_number = 6. Which statement would you write on Line A?
<<big_loop>>
WHILE condition_1 LOOP
<<small_loop>>
FOR i IN 1..10 LOOP
DBMS_OUTPUT.PUT_LINE(i);
--Line A
END LOOP;
END LOOP;

IF v_number = 6 THEN EXIT;
EXIT outer_loop WHEN v_number = 6;
EXIT big_loop WHEN v_number = 6; (*)
EXIT small_loop WHEN v_number = 6;
Incorrect. Refer to Section 4.

10. You want to display multiplication tables for numbers up to 12. The display
should look like this:
1 x 1 = 1
1 x 2 = 2
.....
1 x 12 = 12
2 x 1 = 2
2 x 2 = 4
.....
2 x 12 = 24
3 x 1 = 3
.....
.....
12 x 12 = 144
Which of the following is an efficient way to do this in PL/SQL?

Use two nested FOR loops. (*)
Store all the numbers from 1 to 144 in a table, then fetch and display them using a cursor.
Create a function which accepts two numbers as IN parameters and returns their product.
Invoke the function 144 times.
Write an anonymous block which contains 144 calls to DBMS_OUTPUT, each looking like: DBMS_OUTPUT.PUT_LINE('7 x 9 = 63');

11. Examine the following code fragment:
DECLARE
CURSOR emp_curs IS
SELECT first_name, last_name FROM employees;
v_emp_rec emp_curs%ROWTYPE;
BEGIN
...
FETCH emp_curs INTO v_emp_rec;
DBMS_OUTPUT.PUT_LINE(... Point A ...);
&nbsp...
To display the fetched last name, what should you code at Point A?

v_emp_rec.last_name (*)
v_emp_rec(last_name)
v_emp_rec
last_name
None of the above

12. Assume that you have declared a cursor called C_EMP. Which of the following
statements about C_EMP is correct? (Choose two.) (Choose all correct answers)
You can use c_emp%NOTFOUND to exit a loop. (*)
You can fetch rows when c_emp%ISOPEN evaluates to FALSE.
You can use c_emp%ROWCOUNT to return the number of rows returned by the cursor so far. (*)
You can use c_emp%FOUND after the cursor is closed.


13. The following cursor has been declared:
CURSOR emp_curs IS
SELECT first_name, last_name, job_id, salary
FROM employees;
Which of the following correctly declares a composite record with the same structure as the cursor?

emp_rec emp_rec%ROWTYPE;
emp_rec emp_curs%TYPE;
emp_rec emp_curs%ROWTYPE; (*)
emp_rec cursor%ROWTYPE;

14. Which of the following cursor attributes evaluates to TRUE if the cursor is open?
%ISOPEN (*)
%NOTFOUND
%FOUND
%ROWCOUNT

15. Which of the following cursor attributes is set to the total number of rows returned so far?
%ISOPEN
%NOTFOUND
%FOUND
%ROWCOUNT (*)


16. The employees table contains 11 columns. The following block declares a cursor and a record based on the cursor:
DECLARE
CURSOR emp_curs IS
SELECT * FROM employees;
v_emp_rec emp_curs%ROWTYPE;
A twelfth column is now added to the employees table. Which of the following statements is true?

The declaration of emp_rec must be changed to add an extra field.
The block will still work correctly without any changes to the PL/SQL code. (*)
The block will fail and an INVALID_CURSOR exception will be raised.
An extra scalar variable must be declared to correspond to the twelfth table column.

17. The following code fragment shows a cursor FOR loop:
FOR emp_record IN emp_cursor LOOP ......
Which of the following do NOT need to be coded explicitly? (Choose three.) (Choose all correct answers)
OPEN emp_cursor; (*)
DECLARE CURSOR emp_cursor IS ... emp_record emp_cursor%ROWTYPE; (*)
FETCH emp_cursor INTO emp_record; (*)
END LOOP;

18. What is wrong with the following code?
DECLARE
CURSOR dept_curs IS SELECT * FROM departments;
BEGIN
FOR dept_rec IN dept_curs LOOP
DBMS_OUTPUT.PUT_LINE(dept_curs%ROWCOUNT || dept_rec.department_name);
END LOOP;
DBMS_OUTPUT.PUT_LINE(dept_rec.department_id);
END;
The cursor DEPT_CURS has not been opened.
The implicitly declared record DEPT_REC cannot be referenced outside the cursor FOR loop. (*)
You cannot use %ROWCOUNT with a cursor FOR loop.
The cursor DEPT_CURS has not been closed.
Nothing is wrong, this code will execute successfully.

19. When using a cursor FOR loop, OPEN, CLOSE and FETCH statements should not be explicitly coded. True or False?
True (*)
False

20. Examine the following declaration of a cursor with a parameter. What should be coded at Point A? DECLARE
CURSOR emp_curs(--Point A --) IS
SELECT * FROM employees
WHERE job_id = p_job_id;

p_job_id
ST_CLERK'
p_job_id VARCHAR2(25)
p_job_id VARCHAR2 (*)
job_id VARCHAR2

21. A cursor has been declared as:
CURSOR c_curs (p_param VARCHAR2) IS
SELECT * FROM mytable
WHERE mycolumn = p_param.
Which of the following will open the cursor successfully?

OPEN c_curs(p_param = 'ABC');
OPEN c_curs('ABC'); (*)
OPEN c_curs USING ('ABC');
p_param := 'ABC';
OPEN c_curs(p_param);

22. A PL/SQL block contains the following code:
v_counter := 1;
LOOP
EXIT WHEN v_counter=5;
END LOOP;
v_counter := v_counter + 1;
What is the value of V_COUNTER after the loop is finished?

5
6
1
This is an infinite loop; the loop will never finish. (*)

23. Which one of these is NOT a kind of loop?
ASCENDING loop (*)
FOR loop
Basic loop
WHILE loop

24. Which one of these tasks is best done using a LOOP statement?
Assigning a letter grade to a numerical score
Calculating and displaying the sum of all integers from 1 to 100 (*)
Testing if a condition is true, false or null
Fetching and displaying an employee's last name from the database

25. The EXIT statement can be located anywhere inside a basic loop. True or False?
True (*)
False

26. A PL/SQL block contains the following code:
v_counter := 1;
LOOP
EXIT WHEN v_counter = 5;
v_counter := v_counter + 1;
END LOOP;
What is the value of V_COUNTER after the loop is finished?
5 (*)
6
1
This is an infinite loop; the loop will never finish.

27. What will be the value of v_sal_desc after the following code is executed?

DECLARE
v_salary NUMBER(6,2) := NULL;
v_sal_desc VARCHAR2(10);
v_salary NUMBER(6,2) := NULL;
v_sal_desc VARCHAR2(10);
BEGIN
CASE
WHEN v_salary < 10000 THEN v_sal_desc := 'Low Paid';
WHEN v_salary >= 10000 THEN v_sal_desc := 'High Paid';
END CASE;
END;

High Paid
Low Paid
Null
The code will fail and return an exception (*)

28. You want to display a message which depends on the value of v_grade: if
v_grade = 'A' display 'Very Good', if v_grade = 'B' then display 'Good', and so on.
DECLARE
v_grade CHAR(1);
BEGIN
CASE v_grade
The next line should be

WHEN 'A' THEN (*)
WHEN v_grade = 'A' THEN
WHEN 'A' THEN;
IF 'A' THEN

29. What will be the value of v_result after the following code is executed?
DECLARE
v_grade CHAR(1) := NULL;
v_result VARCHAR2(10);
BEGIN
CASE v_grade
WHEN 'A' THEN v_result := 'Very Good';
WHEN 'F' THEN v_result := 'Poor';
ELSE v_result := 'In Between';
END;
END;

Poor
In Between (*)
Null
Very Good

30. What value will v_answer contain after the following code is executed?
DECLARE
v_age NUMBER:= 18;
v_answer VARCHAR2(10);
BEGIN
v_answer :=
CASE
WHEN v_age < 25 THEN 'Young'
WHEN v_age = 18 THEN 'Exactly 18'
ELSE 'Older'
END CASE;
END;

Exactly 18
Young (*)
Null
Older

31. You want to assign a value to v_result which depends on the value of v_grade: if v_grade
= 'A' set v_result to 'Very Good' and so on.

DECLARE
v_grade CHAR(1);
v_result VARCHAR2(10);
v_grade CHAR(1);
v_result VARCHAR2(10);
BEGIN
v_result := CASE v_grade
The next line should be

WHEN v_grade = 'A' THEN 'Very Good'
WHEN 'A' THEN 'Very Good';
WHEN 'A' THEN v_result := 'Very Good';
WHEN 'A' THEN 'Very Good' (*)

32. You want to declare a cursor which locks each row fetched by the cursor.
Examine the following code:
DECLARE
CURSOR emp_curs IS
SELECT * FROM employees
FOR --Point A
Which of the following can NOT be coded at Point A?

UPDATE;
UPDATE OF salary;
UPDATE OF employees; (*)
UPDATE NOWAIT;

33. User TOM has locked a row in the WORKERS table. Now, user DICK wants to open the following cursor:
CURSOR c IS
SELECT * FROM workers FOR UPDATE NOWAIT;
What will happen when DICK opens the cursor and tries to fetch rows?

TOM's session is rolled back. DICK's session successfully fetches rows from the cursor.

DICK's session waits indefinitely.
Both sessions wait for a few seconds; then the system breaks all locks and both sessions raise an exception.
DICK's session immediately raises an exception. (*)
The c%NOWAIT attribute is set to TRUE.

34. Consider the following cursor:
CURSOR c IS
SELECT e.last_name, e.salary, d.department_name
FROM employees e JOIN departments d
USING(department_id)
WHERE e.last_name='Smith'
FOR UPDATE;
When the cursor is opened and rows are fetched, what is locked?

The whole EMPLOYEES table is locked.
In the EMPLOYEES table, only the 'Smith' rows are locked. Nothing in the
DEPARTMENTS table is locked.
Each 'Smith' row is locked and Smith's matching rows in DEPARTMENTS are locked.
No other rows are locked in either table. (*)
The whole EMPLOYEES and DEPARTMENTS tables are locked.
Nothing is locked because the cursor was not declared with NOWAIT.

35. Which statement best describes when a FOR loop should be used?
When the number of iterations is known (*)
When testing the value in a Boolean variable
When the controlling condition must be evaluated at the start of each iteration


36. Which statement best describes when a WHILE loop shouild be used?
When the number of iterations is known
When repeating a sequence of statements until the controlling condition is no longer true (*)
When assigning a value to a Boolean variable
When testing whether a variable is null

37. Which of the following blocks produces the same output as this block?
BEGIN
FOR i in 1 .. 3 LOOP
DBMS_OUTPUT.PUT_LINE(i);
END LOOP;
END;

DECLARE
i PLS_INTEGER := 0;
BEGIN
WHILE i<3 LOOP
DBMS_OUTPUT.PUT_LINE(i);
i := i + 1;
END LOOP;
END;

DECLARE
i PLS_INTEGER := 0;
BEGIN
WHILE i<3 LOOP
i := i + 1;
DBMS_OUTPUT.PUT_LINE(i);
END LOOP;
END; (*)

DECLARE
i PLS_INTEGER := 0;
BEGIN
WHILE i<3 LOOP
DBMS_OUTPUT.PUT_LINE(i);
END LOOP;
i := i+ 1;
END;

38. Examine the following code:
DECLARE
v_bool BOOLEAN := FALSE;
v_counter NUMBER(4) := 0;
BEGIN
... Line A
END;
Which of the following is NOT valid at line A?

WHILE NOT v_boolean LOOP
WHILE v_boolean AND v_counter < 6 LOOP
WHILE v_counter > 8 LOOP
WHILE v_counter IN 1..5 LOOP (*)

39. In a FOR loop, an implicitly declared counter automatically increases or decreases with each iteration. True or False?
True (*)
False

40. In a WHILE loop, the statements inside the loop must execute at least once. True or False?
True
False (*)

41. What is the correct form of a simple IF statement?
IF condition THEN statement;
END IF; (*)

IF condition;
THEN statement;
END IF;

IF condition
THEN statement
ENDIF;

42. You need to execute a set of statements 10 times, increasing a counter by 1 each
time. Which of the following PL/SQL constructs can do this? (Choose three) (Choose all correct answers)
IF ... THEN ... ELSE
A WHILE loop (*)
CASE ... WHEN ... THEN
A FOR loop (*)
A basic loop (*)

43. Examine the following code:
DECLARE
a BOOLEAN := TRUE;
b BOOLEAN := FALSE;
c BOOLEAN := TRUE;
d BOOLEAN := FALSE;
game char(4) := 'lost';
BEGIN
IF ((a AND b) AND (c OR d))
THEN game := 'won';
END IF;
What is the value of GAME at the end of this block?

NULL
won'
lost' (*)
False

44. What is the correct form of a compound IF statement?

IF condition
THEN statement1
ELSE statement 2;
IF condition
THEN statement1
ELSE statement 2;
END IF;

IF condition;
THEN statement1;
ELSE statement2;
END IF;

IF condition THEN statement1;
ELSE statement2;
END IF; (*)

45. You want to display all locations, and the departments in each location. Examine the following code:
DECLARE
CURSOR loc_curs IS SELECT * FROM locations;
CURSOR dept_curs(p_loc_id NUMBER) IS
SELECT * FROM departments WHERE location_id = p_loc_id;
BEGIN
FOR loc_rec IN loc_curs LOOP
DBMS_OUTPUT.PUT_LINE(loc_rec.city);
FOR dept_rec IN dept_curs(--Point A --) LOOP
DBMS_OUTPUT.PUT_LINE(dept_rec.department_name);
END LOOP;
END LOOP;
END;
What should you code at Point A?

p_loc_id
location_id
null
LOOP ... END LOOP;
loc_rec.location_id (*)

46. Which of the following is a good reason to declare and use multiple cursors in a single PL/SQL block?
Multiple cursors improve performance. They are faster than using a single cursor.
Multiple cursors use less memory than a single cursor.
Multiple cursors allow us to fetch rows from two or more related tables without using a
JOIN. (*)
Multiple cursors are the only way to use cursors with parameters.
Multiple cursors can be opened many times, while a single cursor can be opened only once.

47. When using multiple nested cursors, what kinds of loops can you use?
Cursor FOR loops only.
Basic loops only.
WHILE loops only.
None of the above.
All of the above. (*)