ss

Oracle Tips by Burleson

PL/SQL Code Comments

PL/SQL supports two types of comments. If the commend is only one line, you can use the double hyphen (--) to mark a line as a comment. Multiple lines can be commented by bracketing them with the slash star (/*…*/).

SQL> declare
2    v_line varchar2(40);
3 begin
4    -- this is a single line comment
5    v_line := 'Hello World';
6    dbms_output.put_line (v_line);
7    /* This is a
8        multiple line
9        comment
10   */
11 end;/

Hello World

It has become common to document the code by adding comments that explain not only what the procedure (function or block) does but also defines exactly what variables are passed and how they are changed. This “self documented” code is invaluable in assisting someone who has to later maintain the code. Here is a good example.

SQL> declare
2    /* This anonymous block uses a SQL*Plus
3        variable as input, appends Hello to
4        the front and writes it out to the
5        buffer.
6
7        Requirements:
8        1. v_string must be defined before
               execution
9        2. Must set serveroutput on to retrieve
10            results
11    */
12    v_line varchar2(40):= '&v_string';
13 begin
14    v_line := 'Hello '||v_line;
15    dbms_output.put_line (v_line);
16 end;
17 /

Enter value for v_string: Sammy

old 12: v_line varchar2(40):= '&v_string';
new 12: v_line varchar2(40):= 'Sammy';

Hello Sammy

Next, let’s look at variable declaration and manipulation.

The above book excerpt is from:

Easy Oracle PL/SQL Programming

Get Started Fast with Working PL/SQL Code Examples

ISBN 0-9759135-7-3

John Garmany

http://www.rampant-books.com/book_2005_1_easy_plsql.htm