Section 4 Lesson 5: Iterative Control: Nested Loops

Iterative Control: Nested Loops

 1.  What statement allows you to exit the outer loop at Point A in the following block?
DECLARE
 v_outer_done CHAR(3) := 'NO';
 v_inner_done CHAR(3) := 'NO';
BEGIN
 LOOP -- outer loop
  ...
   LOOP -- inner loop
   ...
   ... -- Point A
   EXIT WHEN v_inner_done = 'YES';
   ...
  END LOOP;
  ...
  EXIT WHEN v_outer_done = 'YES';
  ...
 END LOOP;
END;
(1) Points
     
    EXIT AT v_outer_done = 'YES';
    EXIT WHEN v_outer_done = 'YES'; (*)
    WHEN v_outer_done = YES EXIT;
    EXIT <<outer loop>>;
     
  2.  Which one of these statements about using nested loops is true? (1) Points
     
    All the loops must be labelled
    The outer loop must be labelled, but the inner loop need not be labelled
    The outer loop must be labelled if you want to exit the outer loop from within the inner loop (*)
    Both loops can have the same label
     
  3.  What will be displayed when the following block is executed?
DECLARE
  x NUMBER(6) := 0 ;
BEGIN
  FOR i IN 1..10 LOOP
    FOR j IN 1..5 LOOP
    x := x+1 ;
    END LOOP;
  END LOOP;
  DBMS_OUTPUT.PUT_LINE(x);
END;
(1) Points
     
    5
    10
    15
    50 (*)
     
  4.  When the following code is executed, how many lines of output will be displayed?
BEGIN
  FOR i IN 1..5 LOOP
    FOR j IN 1..8 LOOP
      DBMS_OUTPUT.PUT_LINE(i || ',' || j);
    END LOOP;
    DBMS_OUTPUT.PUT_LINE(i);
  END LOOP;
END;
(1) Points
     
    80
    45 (*)
    14
    41
     
  5.  What type of loop statement would you write for Point A?
BEGIN
  FOR v_outerloop IN 1..3 LOOP
    -- Point A
     DBMS_OUTPUT.PUT_LINE('Outer loop is:'||v_outerloop||
     ' and inner loop is: '||v_innerloop);
     END LOOP;
  END LOOP;
END;
(1) Points
     
    WHILE v_innerloop <=5 LOOP
    FOR v_innerloop 1..5 LOOP (*)
    LOOP
    WHILE v_outerloop<v_innerloop LOOP
     
  6.  Look at the following code:
DECLARE
  v_blue NUMBER(3) := 0;
  v_red NUMBER(3) := 0;
BEGIN
<< blue >> LOOP
  v_blue := v_blue + 1;
  EXIT WHEN v_blue > 10;
  << red >> LOOP
    v_red := v_red + 1;
    EXIT WHEN v_red > 10;
     -- Line A
  END LOOP red;
END LOOP blue;
END;

What should you code at Line A to exit from the outer loop?
(1) Points
     
    EXIT;
    EXIT red;
    EXIT <<blue>>;
    EXIT blue; (*)

Section 4 Lesson 4: Iterative Control: While and For Loops

Iterative Control: While and For Loops
     
  1.  Look at the following code fragment:
i := 2;
WHILE i < 3 LOOP
   i := 4;
   DBMS_OUTPUT.PUT_LINE('The counter is: ' || i);
END LOOP;

How many lines of output will be displayed?
(1) Points
     
    No lines
    One line (*)
    Two lines
    The block will fail because you cannot use DBMS_OUTPUT.PUT_LINE inside a loop.
     
  2.  Look at the following block:
DECLARE
   v_date DATE := SYSDATE;
BEGIN
   WHILE v_date < LAST_DAY(v_date) LOOP
     v_date := v_date + 1;
   END LOOP;
   DBMS_OUTPUT.PUT_LINE(v_date);
END;

If today's date is 17th April 2007, what will be displayed when this block executes?
(1) Points
     
    01-MAY-07
    31-DEC-07
    4/30/2007 (*)
    4/17/2007
     
  3.  Which statement best describes when a FOR loop should be used? (1) Points
     
    When an EXIT WHEN statement must be coded.
    When an implicitly declared counter must increase by 1 in each iteration of the loop. (*)
    When we want to exit from the loop when a Boolean variable becomes FALSE.
    When the statements inside the loop must execute at least once.
     
  4.  You should use a WHILE loop when the number of iterations of the loop is known in advance. True or False? (1) Points
     
    True
    False (*)
     
  5.  Look at this code fragment: FOR i IN 1 .. 3 LOOP i := 4; DBMS_OUTPUT.PUT_LINE('The counter is: ' || i); END LOOP; How many lines of output will be displayed? (1) Points
     
    One
    Three
     Four
     The block will fail because you cannot change the value of i inside the loop. (*)
     
  6.  In a FOR loop, an explicitly declared counter is automatically incremented by 1 for each iteration of the loop. True or False? (1) Points
     
    True
     False (*)
     
 7.  In a WHILE loop, the controlling condition is checked at the start of each iteration. True or False?  (1) Points
     
    True (*)
     False
     
  8.  You want a loop that counts backwards from 10 through 1. How do you code that? (1) Points
     
    FOR i IN 10 .. 1 LOOP
    FOR i IN 1 .. 10 BY -1 LOOP
    FOR i IN REVERSE 1 .. 10 LOOP (*)
    FOR i IN REVERSE 10 .. 1 LOOP

Section 4 Lesson 3: Iterative Control: Basic Loops

Iterative Control: Basic Loops
     
  1.  What will be displayed when this block is executed?
DECLARE
  v_count NUMBER := 10;
  v_result NUMBER;
BEGIN
  LOOP
    v_count := v_count - 1;
    EXIT WHEN v_count < 5;
    v_result := v_count * 2;
  END LOOP;
  DBMS_OUTPUT.PUT_LINE(v_result);
END;
(1) Points
     
    8
    10 (*)
    12
    NULL
     
  2.  For which one of these tasks should you use a PL/SQL loop? (1) Points
     
    Updating the salary of one employee.
    Executing the same set of statements repeatedly until a condition becomes true. (*)
    Deciding whether a value is within a range of numbers.
    Making a decision based on whether a condition is true or not.
     
  3.  Look at this code:
DECLARE
  v_bool BOOLEAN := TRUE;
  v_date DATE;
BEGIN
  LOOP
    EXIT WHEN v_bool;
    SELECT SYSDATE INTO v_date FROM dual;
  END LOOP;
END;

How many times will the SELECT statement execute?
(1) Points
     
    Once.
    Twice.
    Never (the SELECT will not execute at all) (*)
    An infinite number of times because the EXIT condition will never be true
     
  4.  Which kind of loop is this?
i := 10;
LOOP
    i := i + 1;
    EXIT WHEN i > 30;
END LOOP;
(1) Points
     
    A FOR loop.
    A WHILE loop.
    A basic loop. (*)
    An infinite loop.
    A nested loop.
     
  5.  Examine the following code::
DECLARE
  v_count NUMBER := 0;
  v_string VARCHAR2(20);
BEGIN
  LOOP
    v_string := v_string || 'x';
    IF LENGTH(v_string) > 10 THEN
      EXIT;
    END IF;
    v_count := v_count + 1;
  END LOOP;
  DBMS_OUTPUT.PUT_LINE(v_count);
END;
What will be displayed when this block is executed?
(1) Points
     
    9
    10 (*)
    11
    xxxxxxxxxxx
     
  6.  You want to calculate and display the multiplication table for "sevens": 7x1=7, 7x2=14, 7x3=21 and so on. Which kind of PL/SQL construct is best for this?  (1) Points
     
    A loop (*)
    A CASE statement
    IF ... END IF;
    A Boolean variable.
     
  7.  What are the three kinds of loops in PL/SQL?  (1) Points
     
    ascending, descending, unordered
    infinite, finite, recursive
    IF, CASE, LOOP
    FOR, WHILE, basic (*)

     
  8.  How many EXIT statements can be coded inside a basic loop? (1) Points
     
    None.
    One only.
    Two.
     As many as you need, there is no limit. (*)

Section 4 Lesson 2: Conditional Control: Case Statements

Conditional Control: Case Statements

 Section 1
   
  1.  How must you end a CASE expression? (1) Points
     
    END; (*)
    ENDIF;
    END CASE;
    ENDCASE;
     
  2.  Examine the following code:
DECLARE
   v_a BOOLEAN;
   v_b BOOLEAN := FALSE;
   v_c BOOLEAN ;
BEGIN
   v_c := (v_a AND v_b);
   -- Line A
    ....
END;

What is the value of V_C at Line A?
(1) Points
     
    True
    False (*)
    NULL
    Undefined
     
  3.  What will be displayed when the following block is executed?
DECLARE
   v_age1 NUMBER(3);
   v_age2 NUMBER(3);
   v_message VARCHAR2(20);
BEGIN
   CASE
     WHEN v_age1 = v_age2 THEN v_message := 'Equal';
     WHEN v_age1 <> v_age2 THEN v_message := 'Unequal';
     ELSE v_message := 'Undefined';
   END CASE;
   DBMS_OUTPUT.PUT_LINE(v_message);
END;
(1) Points
     
    Equal
    Undefined (*)
    Unequal
    Nothing will be displayed because V_MESSAGE is set to NULL.
     
  4.  Examine the following code:
DECLARE
   v_score NUMBER(3);
   v_grade CHAR(1);
BEGIN
   v_grade := CASE v_score
   -- Line A
   ....

The CASE expression must convert a numeric score to a letter grade: 90 -> A, 80 -> B, 70 -> C and so on. What should be coded at Line A?
(1) Points
     
    WHEN 90 THEN grade := 'A'
    WHEN 90 THEN v_grade := 'A';
    WHEN 90 THEN 'A' (*)
    WHEN 90 THEN 'A';
     
  5.  What will be displayed when the following block is executed?
DECLARE
   v_age NUMBER(3);
   v_gender VARCHAR2(6) := 'Female';
   v_status VARCHAR2(20);
BEGIN
   CASE
     WHEN v_age >= 18 AND v_gender = 'Male' THEN v_status := 'Adult Male';
     WHEN v_age >= 18 AND v_gender = 'Female' THEN v_status := 'Adult Female';
     WHEN v_age < 18 AND v_gender = 'Male' THEN v_status := 'Junior Male';
     WHEN v_age < 18 AND v_gender = 'Female' THEN v_status := 'Junior Female';
     ELSE v_status := 'Other Value';
   END CASE;
   DBMS_OUTPUT.PUT_LINE(v_status);
END;
(1) Points
     
    Adult Male
    Junior Female
    Other Value (*)
    Nothing will be displayed because V_STATUS is set to NULL.
     
  6.  How must you end a CASE statement? (1) Points
     
    END;
    END CASE; (*)
    END IF;
    ENDCASE;
     
  7.  Examine the following code:
DECLARE
  v_score NUMBER(3);
  v_grade CHAR(1);
BEGIN
  CASE v_score
  -- Line A
  ....

The CASE statement must convert a numeric score to a letter grade: 90 -> A, 80 -> B, 70 -> C and so on.
What should be coded at Line A?
(1) Points
     
    WHEN 90 THEN v_grade := 'A'
    WHEN 90 THEN v_grade := 'A'; (*)
    WHEN 90 THEN 'A'
    WHEN 90 THEN 'A';
     
  8.  Look at the following code:
DECLARE
   x BOOLEAN := FALSE;
   y BOOLEAN := FALSE;
   z BOOLEAN ;
BEGIN
   z := (x OR NOT y);
   -- Line A
   ....
END;
What is the value of Z at Line A?
(1) Points
     
    True (*)
    False
    NULL
    An error will occur because you cannot combine two Boolean variables using "NOT".

Section 4 Lesson 1: Conditional Control: IF Statements

Conditional Control: IF Statements

 Section 1
 
  1.  Name three types of control structures in PL/SQL. (Choose three)  (1) Points
   (Choose all correct answers)
   
    LOOP statements (*)
    SELECT statements
    EXCEPTIONS
    IF statements (*)
    CASE statements (*)
   
  2.  You want to repeat a set of statements 100 times, incrementing a counter each time. What kind of PL/SQL control structure would you use? (1) Points
   
    IF...THEN...ELSE
    IF...THEN...ELSIF...ELSE
    CASE...WHEN...THEN
    A loop. (*)
   
  3.  A basic loop is a type of control structure used to change the logical flow of statements in a PL/SQL block. True or False? (1) Points
   
    True (*)
    False
   
  4.  Look at the following (badly written) code:
age := 5;

IF age<30 THEN mature := 'adult';
ELSIF age<22 THEN mature := 'teenager';
ELSIF age<13 THEN mature := 'child';
END IF;
DBMS_OUTPUT.PUT_LINE(mature);

What will be displayed when this code is executed?
(1) Points
   
    child
    teenager
    adult (*)
    adultteenagerchild
   
  5.  Which one of the following is correct syntax for an IF statement? (1) Points
   
    IF condition THEN DO statement1; statement2; END IF;
    IF condition THEN statement1; statement2; END IF; (*)
    IF condition THEN statement1; statement2; ENDIF;
    IF condition THEN statement1; AND statement2; END IF;
   
  6.  We want to execute one of three statements depending on whether the value in V_VAR is 10, 20 or some other value. What should be coded at Line A?
IF v_var = 10 THEN
statement1;
-- Line A
statement2;
ELSE
statement3;
END IF;
(1) Points
   
    ELSE IF v_var = 20 THEN
    ELSIF v_var = 20
    ELSIF v_var = 20 THEN (*)
    IF v_var = 20 THEN
   
  7.  What will be displayed when this block is executed?
DECLARE
   v_birthdate DATE;
BEGIN
   IF v_birthdate < '01-JAN-2000'
   THEN
     DBMS_OUTPUT.PUT_LINE(' Born in the 20th century ');
   ELSE
     DBMS_OUTPUT.PUT_LINE(' Born in the 21st century ');
   END IF;
END;
(1) Points
   
    Born in the 20th century
    Born in the 21st century (*)
    Exception raised because no date given
   
  8.  Which of the following statements are true about any of the PL/SQL conditional control structures such as IF ... , CASE ... and loops? (1) Points
   
    They allow the programmer to use logical tests to determine which statements are executed and which are not.

    They allow a set of statements to be executed repeatedly (i.e. more than once).

    They determine a course of action based on conditions.

    All of the above. (*)
   
  9.  What is wrong with the following trivial IF statement:
IF (v_job='President')
THEN v_salary := 10000;
(1) Points
   
    IF and THEN must be on the same line: IF (v_job='President') THEN ...
    The condition should be coded: IF (v_job := 'President')
    END IF; is missing (*)
    ELSE is missing

   
  10.  What will be displayed when this block is executed?
DECLARE
   v_bool1 BOOLEAN := NULL;
   v_bool2 BOOLEAN := NULL;
   v_char VARCHAR(10) := 'Start';
BEGIN
   IF (v_bool1 = v_bool2) THEN
     v_char:='Equal';
   ELSE v_char:='Not equal';
   END IF;
   DBMS_OUTPUT.PUT_LINE(v_char);
END;
(1) Points
   
    Equal
    Not equal (*)
    Start
    Nothing will be displayed. The block will fail because you cannot compare two null values.
   
  11.  What will be displayed when this block is executed?
DECLARE
   v_bool1 BOOLEAN := TRUE;
   v_bool2 BOOLEAN;
   v_char VARCHAR(4) := 'up';
BEGIN
   IF (v_bool1 AND v_bool2) THEN
     v_char:='down';
   ELSE v_char:='left';
   END IF;
   DBMS_OUTPUT.PUT_LINE(v_char);
END;
(1) Points
   
    up
    down
    left (*)
    null

Section 3 Lesson 2: Retrieving Data in PL/SQL

Retrieving Data in PL/SQL

 Section 1
   
  1.  Look at this PL/SQL block:
DECLARE
   v_count NUMBER;
BEGIN
   SELECT COUNT(*) INTO v_count
   FROM employees WHERE salary > 50000;
END;

No employees earn more than $50,000. Which of the following statements are true? (1) Points
    (Choose all correct answers)
   
    The SELECT will return value 0 into V_COUNT. (*)
    The SELECT will fail because it does NOT return exactly one row.
    The block will fail because variable V_SALARY was not declared.
    The SELECT returns exactly one row. (*)
    The block will fail because no results are displayed to the user.

  2.  Which one of these SQL statements can be directly included in a PL/SQL executable block?  (1) Points
   
    IF... THEN...;
    INSERT INTO...; (*)
    SELECT * FROM DUAL;
    SHOW USER;

  3.  It is good programming practice to create identifiers having the same name as column names. True or False? (1) Points
   
    True
    False (*)
   
  4.  Which of the following is NOT a valid guideline for retrieving data in PL/SQL?  (1) Points
   
    Terminate the SQL statement with a semicolon (;)
    Do NOT use a WHERE clause in SELECT statements. (*)
    Where possible, declare variables using the %TYPE attribute.
    Specify the same number of variables in the INTO clause as database columns in the SELECT clause.
   
  5.  Which SQL statements can be used directly in a PL/SQL block? (Choose two.)  (1) Points
  (Choose all correct answers)
   
    GRANT EXECUTE ON ...
    SELECT * INTO ... (*)
    REVOKE SELECT ON ...
    UPDATE employees SET... (*)
    ALTER TABLE employees ...
   
  6.  Does PL/SQL allow you to have a variable with the same name as a database column? (1) Points
   
    No
    Yes (*)
   
  7.  What will happen when the following block is executed?
DECLARE
    v_last employees.last_name%TYPE;
    v_first employees.first_name%TYPE;
    v_salary employees.salary%TYPE;
BEGIN
    SELECT first_name, last_name
    INTO v_first, v_last, v_salary
    FROM employees WHERE employee_id=100;
END;
(1) Points
   
    The block will fail because the SELECT statement returns more than one row.
    The block will fail because the SELECT is trying to read two columns into three PL/SQL variables. (*)
    The block will fail because V_LAST was declared before V_FIRST.
    The block will execute successfully, and the V_SALARY variable will be set to NULL.
   
  8.  When used in a PL/SQL block, which SQL statement must return exactly one row? (1) Points
   
    INSERT
    UPDATE
    SELECT (*)
    MERGE
    DELETE

Section 3 Lesson 1: Review of SQL DML

Review of SQL DML

Section 1
   
  1.  When inserting a row into a table, the VALUES clause must include a value for every column of the table. True or False?  (1) Points
   
    True
    False (*)
   
  2.  What would be the result of the following statement: DELETE employees;  (1) Points
   
    Nothing, no data will be changed.
    All rows in the employees table will be deleted. (*)
    The statement will fail because it contains a syntax error.
    The row with EMPOYEE_ID=100 will be deleted.

  3.  Is it possible to insert more than one row at a time using an INSERT statement with a VALUES clause?  (1) Points
   
    No, you can only create one row at a time when using the VALUES clause. (*)
    Yes, you can list as many rows as you want, just remember to separate the rows with commas.
    No, there is no such thing as INSERT ... VALUES.
   
  4.  What is wrong with the following statement?
MERGE INTO emps e
USING new_emps ne
ON (e.employee_id = ne.employee_id)
WHEN MATCHED
THEN UPDATE SET ne.salary = e.salary
WHEN NOT MATCHED
THEN INSERT VALUES
(ne.employee_id, ne.first_name, ne.last_name, .... ne.salary, ....);
(1) Points
   
    The UPDATE clause must include the target table name: UPDATE emps SET ....
    The INSERT clause must include a column list as well as a list of column values.
    The SET clause is trying to update the source table from the target table. (*)
    Nothing is wrong, the statement will execute correctly.
   
  5.  You want to modify existing rows in a table. Which of the following are NOT needed in your SQL statement? (Choose two).  (1) Points
   
    A MODIFY clause.
    An UPDATE clause.
    The name of the table.
    The name of the column(s) you want to modify.
    A new value for the column you want to modify (this can be an expression or a subquery).
    A WHERE clause, (*)
   
  6.  What is wrong with the following statement?
DELETE from employees WHERE salary > (SELECT MAX(salary) FROM employees);
(1) Points
   
    You cannot code a subquery inside a DELETE statement.
    You cannot use inequality operators such as "<" and ">" inside a DELETE statement.
    Nothing is wrong, the statement will execute correctly. (*)
   
  7.  Look at this SQL statement:
MERGE INTO old_trans ot
USING new_trans nt
ON (ot.trans_id = nt.trans_id) .... ;

OLD_TRANS is the source table and NEW_TRANS is the target table. True or false?
(1) Points
   
    True
    False (*)
   
  8.  To modify an existing row in a table, you can use the ________ statement.  (1) Points
   
    MODIFY
    INSERT
    ALTER
    UPDATE (*)