returns a dataset containing all Dwarves returns a dataset containing all unmarried Dwarves returns a dataset containing one Dwarf adds a Dwarf; returns dwarf_id updates a Dwarf returns a dataset containing all Mountains returns a dataset containing one Mountain adds a Mountain; returns mountain_id updates a Mountain marries two Dwarves returns a dataset containing all Dwarves returns a dataset containing all unmarried Dwarves returns a dataset containing one Dwarf adds a Dwarf; returns dwarf_id updates a Dwarf returns a dataset containing all Mountains returns a dataset containing one Mountain adds a Mountain; returns mountain_id updates a Mountain marries two Dwarves returns a dataset containing all Dwarves returns a dataset containing all unmarried Dwarves returns a dataset containing one Dwarf adds a Dwarf; returns dwarf_id updates a Dwarf returns a dataset containing all Mountains returns a dataset containing one Mountain adds a Mountain; returns mountain_id updates a Mountain marries two Dwarves