A character set (token) comprises a series of characters that are combined to form a lexical unit. A distinction is made between regular and delimiter tokens.
<token> ::= <regular_token> | <delimiter_token>
<delimiter_token> ::= <vertical_slash> | , | . | + | - | * | /
| < | > | <> | != | = | <= | >=
| ~= <! for computers with ASCII code !>
| ~< <! for computers with ASCII code !>
| ~> <! for computers with ASCII code !>
<vertical_slash> ::= |
SELECT * FROM reservation
ALTER TABLE reservation DROP FOREIGN KEY customer_reservation
Each token can be followed by any number of blanks. Each regular token regular_token must be followed by a delimiter_token or a blank.
Double quotation marks within a special identifier are represented by two consecutive quotation marks.