% A "normal" lookup
city('New York', Cityid), usr(Cityid, Name, Id).

% An id-less query. Maybe the engine notices the join and transforms this into the prior behind the scenes.
% Maybe an invented built-in like references/4 cause the transformation.
:- references( 'USR', 'CITY_ID', 'USR', 'CITY_ID' ).
usr( city( 'New York' ), Name ).