根据纬度/经度在20公里内选择

问题描述

我有一个按照以下示例构建的 mysql 表:

i have a mysql table structured as per the example below:

POSTAL_CODE_ID|PostalCode|City|Province|ProvinceCode|CityType|Latitude|Longitude
7|A0N 2J0|Ramea|Newfoundland|NL|D|48.625599999999999|-58.9758
8|A0N 2K0|Francois|Newfoundland|NL|D|48.625599999999999|-58.9758
9|A0N 2L0|Grey River|Newfoundland|NL|D|48.625599999999999|-58.9758

现在我要做的是创建一个查询，该查询将选择搜索位置选定公里范围内的结果

now what i am trying to do is create a query that will select results within selected kilometers of a searched location

假设他们搜索灰色河流"并选择查找 20 公里内的所有结果"

so lets say they search for "grey river" and select "find all results within 20 kilometers"

显然应该选择灰河"，但也应该根据经纬度选择灰河20公里范围内的所有位置.

it should obviously select "grey river", but it should also select all locations within 20 kilometers of grey river based on the latitudes and longitudes.

我真的不知道该怎么做.我已经阅读了半正弦公式，但不知道如何将其应用于 mysql SELECT.

i really have no idea how to do this. i've read up on the haversine formula but have no idea how to apply this to a mysql SELECT.

任何帮助将不胜感激.

推荐答案

SELECT  *
FROM    mytable m
JOIN    mytable mn
ON      ACOS(COS(RADIANS(m.latitude)) * COS(RADIANS(mn.latitude)) * COS(RADIANS(mn.longitude) - RADIANS(m.longitude)) + SIN(RADIANS(m.latitude)) * SIN(radians(mn.latitude))) <= 20 / 6371.0
WHERE   m.name = 'grey river'

如果您的表是 MyISAM，您可能希望以原生几何格式存储您的点并在其上创建一个 SPATIAL 索引:

If your table is MyISAM you may want to store your points in a native geometry format and create a SPATIAL index on it:

ALTER TABLE mytable ADD position POINT;

UPDATE  mytable
SET     position = POINT(latitude, longitude);

ALTER TABLE mytable MODIFY position NOT NULL;

CREATE SPATIAL INDEX sx_mytable_position ON mytable (position);

SELECT  *
FROM    mytable m
JOIN    mytable mn
ON      MBRContains
                (
                LineString
                        (
                        Point
                                (
                                X(m.position) - 0.009 * 20,
                                Y(m.position) - 0.009 * 20 / COS(RADIANS(X(m.position)))
                                ),
                        Point
                                (
                                X(m.position) + 0.009 * 20,
                                Y(m.position) + 0.009 * 20 / COS(RADIANS(X(m.position))
                                )
                        ),
                mn.position
                )
        AND ACOS(COS(RADIANS(m.latitude)) * COS(RADIANS(mn.latitude)) * COS(RADIANS(mn.longitude) - RADIANS(m.longitude)) + SIN(RADIANS(m.latitude)) * SIN(radians(mn.latitude))) <= 20 / 6371.0
WHERE   m.name = 'grey river'

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