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Oracle PL/SQL Language Pocket Reference, Second Edition by Chip Dawes, Bill Pribyl, Steven Feuerstein

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PL/SQL Language Fundamentals

This section summarizes the fundamental components of the PL/SQL language: characters, identifiers, literals, delimiters, use of comments and pragmas, and construction of statements and blocks.

PL/SQL Character Set

The PL/SQL language is constructed from letters, digits, symbols, and whitespace, as defined in the following table:

Type

Characters

Letters

A-Z, a-z

Digits

0-9

Symbols

~!@#$%^&*(  )_-+=|[ ]{ }:;"'< >,.?/ ^

Whitespace

space, tab, newline, carriage return

Characters are grouped together into four lexical units: identifiers, literals, delimiters, and comments.

Identifiers

Identifiers are names for PL/SQL objects such as constants, variables, exceptions, procedures, cursors, and reserved words. Identifiers have the following characteristics:

  • Can be up to 30 characters in length

  • Cannot include whitespace (space, tab, carriage return)

  • Must start with a letter

  • Can include a dollar sign ($), an underscore ( _ ), and a pound sign (#)

  • Are not case-sensitive

In addition, you must not use PL/SQL’s reserved words as identifiers. For a list of those words, see the table in the final section in this book, Section 1.20.

If you enclose an identifier within double quotes, then all but the first of these rules are ignored. For example, the following declaration is valid:

DECLARE
   "1 ^abc"  VARCHAR2(100);
BEGIN
   IF "1 ^abc" IS NULL THEN ...
END;

Boolean, Numeric, and String Literals

Literals are specific values not represented by identifiers. For example, ...

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