How to search the site for products based on geolocation?

Question

PHP

There is an Internet site on php + mysql for sellers and buyers. In the database, sellers have fields with their city. The site has a slider to select 100km, 200km, 300km, etc.
It is necessary, using geolocation, to search by goods so that the user is shown the goods of those sellers who are not further than the distance specified by the slider.
PS The search is self-written, if necessary I can use another one, the site is uploaded to a hosting that sphinx does not support, and also does not support a bunch of other similar searches.

Answer 1

https://www.percona.com/blog/2013/10/21/using-the-...