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 non-first 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:
ALL AND ANY AS ASC AVG BETWEEN BY COUNT CURRENT_DATE CURRENT_TIME CURRENT_TIMESTAMP DELETE DESC DISTINCT EMPTY EXISTS |
FALSE FETCH FROM GROUP HAVING IN INNER IS JOIN LEFT LIKE MAX MEMBER MIN MOD NEW |
NOT NULL OBJECT OF OUTER OR ORDER SELECT SOME SUM TRIM TRUE UNKNOWN UPDATE UPPER WHERE |
It is not recommended that you use a SQL keyword as an identifier, because the list of keywords may expand to include other reserved SQL words in the future.