sql - 在postgresql中按经纬度查找最近的位置

Question

您好，我正在尝试在 postgresql 数据库中按纬度和经度查找最近的位置。但是当我运行以下查询时，它显示列距离不存在。

ERROR:  column "distance" does not exist
LINE 1: ... ) ) ) AS distance FROM station_location   HAVING distance <...
                                                             ^
********** Error **********

ERROR: column "distance" does not exist
SQL state: 42703
Character: 218

CREATE TABLE station_location
(
  id bigint NOT NULL DEFAULT nextval('location_id_seq'::regclass),
  state_name character varying NOT NULL,
  country_name character varying NOT NULL,
  locality character varying NOT NULL,
  created_date timestamp without time zone NOT NULL,
  is_delete boolean NOT NULL DEFAULT false,
  lat double precision,
  lng double precision,
  CONSTRAINT location_pkey PRIMARY KEY (id)
)

SELECT  *,( 3959 * acos( cos( radians(6.414478) ) * cos( radians( lat ) ) * cos( radians( lng ) - radians(12.466646) ) + sin( radians(6.414478) ) * sin( radians( lat ) ) ) ) AS distance 
FROM station_location
HAVING distance < 5
ORDER BY distance
LIMIT 20;

Answer 1

后地理信息系统

不要在这样的 table 上存储经纬度。而是使用 PostGIS 几何或 geography type .

CREATE EXTENSION postgis;

CREATE TABLE foo (
  geog geography;
);

CREATE INDEX ON foo USING gist(geog);

INSERT INTO foo (geog)
  VALUES (ST_MakePoint(x,y));

现在需要查询的时候可以用KNN ( <-> )这实际上会在索引上执行此操作。

SELECT *
FROM foo
ORDER BY foo.geog <-> ST_MakePoint(x,y)::geography;

在您的查询中，您明确拥有 HAVING distance < 5 .您也可以在索引上执行此操作。

SELECT *
FROM foo
WHERE ST_DWithin(foo.geog, ST_MakePoint(x,y)::geography, distance_in_meters)
ORDER BY foo.geog <-> ST_MakePoint(x,y)::geography;

如果所有点都在 distance_in_meters 之外，这将确保不会返回任何内容.

另外x和y是十进制数ST_MakePoint(46.06, 14.505)