[Pxtl]

That seems clumsy.

I would think the right approach to "SQL without LEFT JOIN" would be just to focus on making pulling down multiple related tables as distinct resultsets in a single query easier and have the client code work with a graph instead of hammering everything into a single tabular layout. Or leave the concept of "connect these two tables together and make them NULL where not applicable" as an exercise for the client.

[maxdemarzi]

Quite the opposite. The idea is to move as much of the business logic into the database. “Rel” definitions are meant to be written once and reused everywhere. Instead of letting the client decide different business logic every time, you capture and control it in one place.