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google-mapsgoogle-maps-api-3

How to search nearby places stored in my database?

I'm developing a web app where the user sets a place in a map (Google Maps API) and I store the coordinates in a database.

At another page, I want to do a search which consists in getting my local coordinates and retrieve nearby places previously stored at my database based on a radius.

How can I do this?

Solution

  • You can use what is called the Haversine formula.

    For MySQL:

    SELECT 
  *, 
  (
    3959 * acos(
      cos(
        radians(input_lat)
      ) * cos(
        radians(lat)
      ) * cos(
        radians(lng) - radians(input_lng)
      ) + sin(
        radians(input_lat)
      ) * sin(
        radians(lat)
      )
    )
  ) AS distance 
FROM 
  your_table 
HAVING 
  distance < 5

    Where input_lat and input_lng are the coordinates of your point, and lat / lng are your table columns. The above will list the locations within a 5 miles range.

    Replace 3959 by 6371 to change to kilometers.