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. (*)