The shame, to me, is that SQL is _unnecessarily_ clunky with producing query results with nested/heirarchical data. The relational model allows for any given value (field or cell value) to be itself a relation, but SQL doesn't make it easy to express such a query or return such a value from the database (as Jamie says - often the API server has to "perform the join again" to put it in nested form, due to this limitation).
The shame, to me, is that SQL is _unnecessarily_ clunky with producing query results with nested/heirarchical data. The relational model allows for any given value (field or cell value) to be itself a relation, but SQL doesn't make it easy to express such a query or return such a value from the database (as Jamie says - often the API server has to "perform the join again" to put it in nested form, due to this limitation).