PL/SQL - Basic Syntax

Basic Syntax of a PL/SQL program is:

DECLARE
<declarations section>
BEGIN
<executable section>
EXCEPTION
<exception handling section>
END;

My 'First PL/SQL' Program:

DECLARE
v_message varchar2(20):= 'My first PLSQL program!';
BEGIN
dbms_output.put_line(v_message);
END;
/

Identifiers

PL/SQL identifiers are constants, variables, exceptions, procedures, cursors, and reserved words. The identifiers consist of a letter optionally followed by more letters, numerals, dollar signs, underscores, and number signs and should not exceed 30 characters.

By default, identifiers are not case-sensitive. So you can use integer or INTEGER to represent a numeric value. You cannot use a reserved keyword as an identifier.

Delimiters

List of PL/SQL delimiters:

Delimiter	Description
+, -, *, /	Addition, subtraction/negation, multiplication, division
%	Attribute indicator
'	Character string delimiter
.	Component selector
(,)	Expression or list delimiter
:	Host variable indicator
,	Item separator
"	Quoted identifier delimiter
=	Relational operator
@	Remote access indicator
;	Statement terminator
:=	Assignment operator
=>	Association operator
||	Concatenation operator
**	Exponentiation operator
<<, >>	Label delimiter (begin and end)
/*, */	Multi-line comment delimiter (begin and end)
--	Single-line comment indicator
..	Range operator
<, >, <=, >=	Relational operators
<>, '=, ~=, ^=	Different versions of NOT EQUAL

Comments

There are single-line and multi-line comments available in PL/SQL.

DECLARE
-- variable declaration
v_message varchar2(20):= 'My first PLSQL example!';
BEGIN
/*
* This is PL/SQL executable statement(s)
*/
dbms_output.put_line(message);
END;
/

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