Hash join: Difference between revisions

=={{header|Prolog}}==

<lang Prolog>% Name/Age

person_age('Jonah', 27).

person_age('Alan', 18).

person_age('Glory', 28).

person_age('Popeye', 18).

person_age('Alan', 28).

% Character/Nemesis

character_nemisis('Jonah', 'Whales').

character_nemisis('Jonah', 'Spiders').

character_nemisis('Alan', 'Ghosts').

character_nemisis('Alan', 'Zombies').

character_nemisis('Glory', 'Buffy').

join_and_print :-

format('Age\tName\tCharacter\tNemisis\n\n'),

forall(

(person_age(Person, Age), character_nemisis(Person, Nemesis)),

format('~w\t~w\t~w\t\t~w\n', [Age, Person, Person, Nemesis])

).</lang>

{{out}}

<pre>

?- join_and_print.

Age Name Character Nemisis

27 Jonah Jonah Whales

27 Jonah Jonah Spiders

18 Alan Alan Ghosts

18 Alan Alan Zombies

28 Glory Glory Buffy

28 Alan Alan Ghosts

28 Alan Alan Zombies

true.

</pre>