PostgreSQL `With` Clause

postgres-with-clause

with parcel_ids as (select id from parcels where ranch_id = 57),
    zone_ids as (select id from zones where parcel_id in (select id from parcel_ids))
select extract(month from date) as month, category, sub_category, count(*) from events where (area_type = 'parcel' and area_id in (select id from parcel_ids)) or (area_type = 'zone' and area_id in (select id from zone_ids))
    group by extract(month from date), category, sub_category;