The document discusses PL/SQL programming, highlighting the use of comments, variable declarations, and the dbms_output.put_line statement for displaying information. It explains that PL/SQL is not a standalone language and relies on Oracle tools for user input with substitution variables. Additionally, it describes how to enable and configure output through the dbms_output package in SQL*Plus.

1. PL/SQL

17. • https://www.slideshare.net/slideshow/class-01-23894673/23894673#8

19. The PL/SQL Comments
• The PL/SQL supports single-line and multi-line comments. All characters available
inside any comment are ignored by the PL/SQL compiler.
• The PL/SQL single-line comments start with the delimiter -- (double hyphen)
• Multi-line comments are enclosed by /* and */.
DECLARE
-- variable declaration
message varchar2(20):= 'Hello, World!';
BEGIN
/*
* PL/SQL executable statement(s)
*/
dbms_output.put_line(message);
END;

20. • We noted earlier that PL/SQL is not a stand-alone programming
language; rather, it exists only as a tool within the Oracle environment.
• As a result, it does not really have any capabilities to accept input
from a user.
• The lack of this ability is compensated with the special feature of the
SQL Developer and SQL*Plus tools called a substitution variable.
• Similarly, it is often helpful to provide the user with some pertinent
information with the help of the DBMS_OUTPUT.PUT_LINE
statement.

21. • DBMS_OUTPUT.PUT_LINE statement may be used in a script to
display information on the screen.
• The DBMS_OUTPUT.PUT_LINE is a call to the procedure
PUT_LINE. This procedure is a part of the DBMS_OUTPUT package
that is owned by the Oracle user SYS.
• The DBMS_OUTPUT.PUT_LINE statement writes information to the
buffer for storage.
• After a program has completed, the information from the buffer is
displayed on the screen. The size of the buffer can be set between 2000
and 1 million bytes.
• To see the results of the DBMS_OUTPUT.PUT_LINE statement on the
screen, you need to enable it.

22. • https://www.pearsonitcertification.com/articles/article.aspx?p=317891
9&seqNum=3#:~:text=Oracle%20user%20SYS.-,The%20DBMS_OU
TPUT.,2000%20and%201%20million%20bytes
.

23. • To enable the DBMS_OUTPUT statement in SQL*Plus, you enter one of the following
statements before the PL/SQL block:
SET SERVEROUTPUT ON;
or
SET SERVEROUTPUT ON SIZE 5000;
• The first SET statement enables the DBMS_OUTPUT.PUT_LINE statement, with the
default value for the buffer size being used.
• The second SET statement not only enables the DBMS_OUTPUT.PUT_LINE statement
but also changes the buffer size from its default value to 5000 bytes.
• Similarly, if you do not want information to be displayed on the screen by the
DBMS_OUTPUT.PUT_LINE statement, you can issue the following SET command prior
to the PL/SQL block:
SET SERVEROUTPUT OFF;