How to find the nearest city from a list based on current coordinates?

Question

Database

There is a database of cities with coordinates (name, lat, lon).
There is a user's current location (lat, lon).
How to correctly calculate the nearest city from the list based on the user's current location?

Answer 1

postgis.net/docs/manual-1.3/ch03.html#id434832
For example, to find all objects with 100 meters of POINT(1000 1000) the following query would work well:

SELECT * FROM geotable 
  WHERE ST_DWithin(geocolumn, 'POINT(1000 1000)', 100.0);