Token 

A character set or token comprises a series of characters that are combined to form a lexical unit. A distinction is made between regular and delimiter tokens.

Syntax

<token> ::= <regular_token> | <delimiter_token>

regular_token, delimiter_token

SELECT * FROM reservation
ALTER TABLE reservation DROP FOREIGN KEY customer_reservation

Explanation

Each token can be followed by any number of blanks. Each regular token must be followed by a delimiter token or a blank.

Double_quotes within a special_identifier are represented by two consecutive quotes.