Identifiers (The Java EE 6 Tutorial)

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Identifiers

An identifier is a sequence of one or more characters. The first character must be a valid first character (letter, $, _) in an identifier of the Java programming language, hereafter in this chapter called simply “Java”. Each subsequent character in the sequence must be a valid nonfirst character (letter, digit, $, _) in a Java identifier. (For details, see the Java SE API documentation of the isJavaIdentifierStart and isJavaIdentifierPart methods of the Character class.) The question mark (?) is a reserved character in the query language and cannot be used in an identifier.

A query language identifier is case-sensitive, with two exceptions:

  • Keywords

  • Identification variables

An identifier cannot be the same as a query language keyword. Here is a list of query language keywords:

ABS

ALL

AND

ANY

AS

ASC

AVG

BETWEEN

BIT_LENGTH

BOTH

BY

CASE

CHAR_LENGTH

CHARACTER_LENGTH

CLASS

COALESCE

CONCAT

COUNT

CURRENT_DATE

CURRENT_TIMESTAMP

DELETE

DESC

DISTINCT

ELSE

EMPTY

END

ENTRY

ESCAPE

EXISTS

FALSE

FETCH

FROM

GROUP

HAVING

IN

INDEX

INNER

IS

JOIN

KEY

LEADING

LEFT

LENGTH

LIKE

LOCATE

LOWER

MAX

MEMBER

MIN

MOD

NEW

NOT

NULL

NULLIF

OBJECT

OF

OR

ORDER

OUTER

POSITION

SELECT

SET

SIZE

SOME

SQRT

SUBSTRING

SUM

THEN

TRAILING

TRIM

TRUE

TYPE

UNKNOWN

UPDATE

UPPER

VALUE

WHEN

WHERE

It is not recommended that you use an SQL keyword as an identifier, because the list of keywords may expand to include other reserved SQL words in the future.

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