6.7 Lateral joins

6.52

select
    a.neighborhood,
    trees.trees_per_sq_meter
from
    nyc_neighborhoods a
    cross join lateral (
        select
            count(ogc_fid) / a.area :: numeric as trees_per_sq_meter
        from
            nyc_2015_tree_census
        where
            a.neighborhood = neighborhood
    ) trees
order by
    trees.trees_per_sq_meter desc