Mysql in request distance

Question

Functions

$lat = '25.7742658';
$lng = '-80.1936589';
$miles = 30;

Inquiry

SELECT *, 
   ( 3959 * acos( cos( radians($lat) ) 
   * cos( radians( lat ) ) 
   * cos( radians( lng ) - radians($lng) ) 
   + sin( radians($lat) ) 
   * sin( radians( lat ) ) ) ) AS distance 
FROM locations 
HAVING distance < $miles 
ORDER BY distance 
LIMIT 0, 20

I have a database table with 4 columns:

• unique identificator
• city ​​name
• latitude (lat)
• longitude (lng)

I use the query from above to return places that are within a given number of miles from the specified coordinates. It seems to work, but I'm not sure how accurate it is. I am curious to know if the request is good or if you have a better solution.

Answer 1

which looks like a valid distance request in a big circle.

What are you worried about wrt accuracy?

Answer 2

mysql, " MySQL", MySQL 5.6. :

https://www.percona.com/blog/2013/10/21/using-the-new-mysql-spatial-functions-5-6-for-geo-enabled-applications/

PDF:

http://www.arubin.org/files/geo_search.pdf