php - Get nearest places on Google Maps, using MySQL spatial data

Question

I have a database with a list of stores with latitudes and longitudes of each. So based on the current (lat, lng) location that I input, I would like to get a list of items from those within some radius like 1 km, 5km etc?

What should be the algorithm? I need the PHP code for algorithm itself.

Answer 1

You just need use following query.

For example, you have input latitude and longitude 37 and -122 in degrees. And you want to search for users within 25 miles from current given latitude and longitude.

SELECT item1, item2, 
    ( 3959 * acos( cos( radians(37) ) 
                   * cos( radians( lat ) ) 
                   * cos( radians( lng ) 
                       - radians(-122) ) 
                   + sin( radians(37) ) 
                   * sin( radians( lat ) ) 
                 )
   ) AS distance 
FROM geocodeTable 
HAVING distance < 25 
ORDER BY distance LIMIT 0 , 20;

If you want search distance in kms, then replace 3959 with 6371 in above query.

You can also do this like:

1. Select all Latitude and longitude

2. Then calculate the distance for each record.

3. The above process can be done with multiple redirection.

For optimizing query you can use Stored Procedure.

And this can also help you.