Lab 2.2 Exercises
2.2.1 Use Substitution Variables
In this exercise, you will calculate the square of a number. The value of the number will be provided with the help of a substitution variable. Then the result will be displayed on the screen.
Create the following PL/SQL script:
-- ch02_1a.sql, version 1.0
SET SERVEROUTPUT ON
DECLARE
v_num NUMBER := &sv_num;
v_result NUMBER;
BEGIN
v_result := POWER(v_num, 2);
DBMS_OUTPUT.PUT_LINE ('The value of v_result is: '||
v_result);
END;
Execute the script, and then answer the following questions:
| a) |
If the value of v_num is equal to 10, what output is printed on the screen? | | b) |
What is the purpose of using a substitution variable? | | c) |
Why is it considered a good practice to enclose substitution variables with single quotes for string datatypes? |
2.2.2 Use the DBMS_OUTPUT.PUT_LINE Statement
In this exercise, you will determine the day of the week based on today's date. You will then display the results on the screen.
Create the following PL/SQL script:
-- ch02_2a.sql, version 1.0
SET SERVEROUTPUT ON
DECLARE
v_day VARCHAR2(20);
BEGIN
v_day := TO_CHAR(SYSDATE, 'Day');
DBMS_OUTPUT.PUT_LINE ('Today is '||v_day);
END;
Execute the script, and then answer the following questions:
| a) |
What was printed on the screen? | | b) |
What will be printed on the screen if the statement SET SERVEROUTPUT OFF is issued? Why? | | c) |
How would you change the script to display the time of the day as well? |
| 
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