rule1: 'ACTIVATE' ('DATABASE' | 'DB') database-alias ('' | 'USER' username ( '' | 'USING' password ) )
rule2: select-clause from-clause ('' | where-clause) ('' | group-by-clause) ('' | having-clause)
rule3: 'SELECT' ('ALL' | '' | 'DISTINCT') ( '*' | ( expression ( '' | ( ('' | 'AS' ) new-column-name ) ) | exposed-name '.*' )(/,/ *) )