Spowoduje to usunięcie drugiego miasta w pobliżu miasta o tej samej nazwie w tym samym kraju:
delete from climate.maxmind_city mc where id in (
select
max(c1.id)
from
climate.maxmind_city c1,
climate.maxmind_city c2
where
c1.id <> c2.id and
c1.country = c2.country and
c1.name = c2.name and
earth_distance(
ll_to_earth( c1.latitude_decimal, c1.longitude_decimal ),
ll_to_earth( c2.latitude_decimal, c2.longitude_decimal ) ) <= 35
group by
c1.country, c1.name
order by
c1.country, c1.name
)
