60 lines
1.5 KiB
Plaintext
60 lines
1.5 KiB
Plaintext
create schema v;
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-- create a table to store geographic points
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create table v.places (
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id serial primary key,
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name text,
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geom geometry(point, 4326) -- using WGS 84 coordinate system
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);
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-- insert some sample geographic points into the places table
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insert into v.places (name, geom)
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values
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('place_a', st_setsrid(st_makepoint(-73.9857, 40.7484), 4326)), -- latitude and longitude for a location
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('place_b', st_setsrid(st_makepoint(-74.0060, 40.7128), 4326)), -- another location
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('place_c', st_setsrid(st_makepoint(-73.9687, 40.7851), 4326)); -- yet another location
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-- calculate the distance between two points (in meters)
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select
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a.name as place_a,
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b.name as place_b,
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st_distance(a.geom::geography, b.geom::geography) as distance_meters
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from
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v.places a,
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v.places b
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where
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a.name = 'place_a'
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and b.name = 'place_b';
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place_a | place_b | distance_meters
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---------+---------+-----------------
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place_a | place_b | 4309.25283351
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(1 row)
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-- find all places within a 5km radius of 'place_a'
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select
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name,
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st_distance(
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geom::geography,
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(
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select
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geom
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from
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v.places
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where
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name = 'place_a'
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)::geography) as distance_meters
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from
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v.places
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where
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st_dwithin(
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geom::geography,
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(select geom from v.places where name = 'place_a')::geography,
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5000
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)
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and name != 'place_a';
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name | distance_meters
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---------+-----------------
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place_b | 4309.25283351
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place_c | 4320.8765634
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(2 rows)
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drop schema v cascade;
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NOTICE: drop cascades to table v.places
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