Character Set (token) 

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.

Syntax

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

<regular_token>   ::= <literal> | <key_word> | <identifier> | <parameter_name>

<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
'Reisen10'

Explanation

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.