MySQL Great Circle Distance (Haversine formula)

前端 未结 9 1380
栀梦
栀梦 2020-11-21 06:53

I\'ve got a working PHP script that gets Longitude and Latitude values and then inputs them into a MySQL query. I\'d like to make it solely MySQL. Here\'s my current PHP Cod

9条回答
  •  不知归路
    2020-11-21 07:15

    I have had to work this out in some detail, so I'll share my result. This uses a zip table with latitude and longitude tables. It doesn't depend on Google Maps; rather you can adapt it to any table containing lat/long.

    SELECT zip, primary_city, 
           latitude, longitude, distance_in_mi
      FROM (
    SELECT zip, primary_city, latitude, longitude,r,
           (3963.17 * ACOS(COS(RADIANS(latpoint)) 
                     * COS(RADIANS(latitude)) 
                     * COS(RADIANS(longpoint) - RADIANS(longitude)) 
                     + SIN(RADIANS(latpoint)) 
                     * SIN(RADIANS(latitude)))) AS distance_in_mi
     FROM zip
     JOIN (
            SELECT  42.81  AS latpoint,  -70.81 AS longpoint, 50.0 AS r
       ) AS p 
     WHERE latitude  
      BETWEEN latpoint  - (r / 69) 
          AND latpoint  + (r / 69)
       AND longitude 
      BETWEEN longpoint - (r / (69 * COS(RADIANS(latpoint))))
          AND longpoint + (r / (69 * COS(RADIANS(latpoint))))
      ) d
     WHERE distance_in_mi <= r
     ORDER BY distance_in_mi
     LIMIT 30
    

    Look at this line in the middle of that query:

        SELECT  42.81  AS latpoint,  -70.81 AS longpoint, 50.0 AS r
    

    This searches for the 30 nearest entries in the zip table within 50.0 miles of the lat/long point 42.81/-70.81 . When you build this into an app, that's where you put your own point and search radius.

    If you want to work in kilometers rather than miles, change 69 to 111.045 and change 3963.17 to 6378.10 in the query.

    Here's a detailed writeup. I hope it helps somebody. http://www.plumislandmedia.net/mysql/haversine-mysql-nearest-loc/

提交回复
热议问题