method builds a query that produces all combinations of two queries'
outputs that together meet some condition. It's a wrapper for SQL's
For any queries
you can call
) provided that:
abstract_mapper<bool>(in practice it will be a
mappers will both be visible
) returns a
(that's a kind of query) with the following characteristics:
r's value types respectively.
>, whose two member mappers are identical to
r's value mappers respectively.
std::tuples, formed from each combination of the outputs of
r, for which
) is interchangeable with
), which has exactly the same characteristics.
const query<std::tuple<screen, movie>> current_screenings = screens.inner_join(movies, screens->current_movie_id == movies->id);