RELATIONAL_SCHEME ::= TABLES RELATIONSHIPS?

TABLE-ID ::= STRING

COLUMN-ID ::= STRING

RELATION-ID ::= STRING

TABLES ::= 'Tables'

(TABLE-ID'('COLUMN-ID ':' DATA-TYPE? 'key'? (',' COLUMN-ID ':' DATA-TYPE? 'key'?)*')')*

RELATIONSHIPS ::= 'Relationships'

((TABLE-ID'.'COLUMN-ID)+ '->' (TABLE-ID'.'COLUMN-ID TYPE)+)*

TYPE ::= 'one_to_one' | 'one_to_many' | 'many_to_one' | 'many_to_many'

DATA-TYPE ::= 'boolean' | 'binary' | 'date' | 'datetime' | 'decimal' | 'float' |

'integer' | 'string' | 'text' | 'time' | 'timestamp'