The PL/SQL Character Set

The PL/SQL Character Set

A PL/SQL program consists of a sequence of statements, each of which is made up of one or more lines of text. Text is made up of combinations of the characters shown in Table.

Table : PL/SQL Character Set

Type	Characters
Letters	A-Z, a-z
Digits	0-9
Symbols	~ ! @ # $ % & * ( ) _ - + = | [ ] { } : ; " ' < > , . ? /
Whitespace	Tab, space, carriage return

Note that PL/SQL is a case-insensitive language. Uppercase letters are treated the same way as lowercase letters except when the characters are surrounded by single quotes (when they are literal strings) or represent the value of a character variable.

Every valid statement in PL/SQL, from declaration to executable statement to keyword, is made up of various combinations of the above characters. Now you just have to figure out how to put them all together!

A number of these characters -- both singly and in combination with other characters -- have a special significance in PL/SQL. Table 2 lists these special symbols.

Table 2: Simple and Compound Symbols in PL/SQL

Symbol	Description
;	Semicolon: statement terminator
%	Percent sign: attribute indicator (cursor attributes like %ISOPEN and indirect declaration attributes like %ROWTYPE). Also used as multibyte wildcard symbol, as in SQL.
_	Single underscore: single-byte wildcard symbol, as in SQL
:	Colon: host variable indicator, such as :block.item in Oracle Forms
**	Double asterisk: exponentiation operator
< > and !=	"Not equals"
||	Double vertical bar: concatenation operator
<< and >>	Label delimiters
<= and >=	Relational operators
:=	Assignment operator
=>	Association operator for positional notation
--	Double dash: single-line comment indicator
/* and */	Beginning and ending multiline comment block delimiters

Characters are grouped together into lexical units, also called atomics of the language, because they are the smallest individual components. A lexical unit in PL/SQL is any of the following:

• Identifier
• Literal
• Delimiter
• Comment