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