How to calculate distance to coordinates?

Question

PHP

There is a table in the database while there id, city_name, there will probably be more coords (string)
There are user coordinates.
It is necessary to find the city closest to the user.
I can’t understand how to calculate and most importantly how best to store the coordinates of the city for this.
It would be possible to get the city by api from google or yandex, but the list of cities is limited, there are 25 cities. Over time, there will be more of course, but not everything is accurate.
What do you advise?

Answer 1

https://www.google.ru/#q=%D0%BE%D0%BF%D1%80%D0%B5%...