Logan Henson, a developer at Tighten, wrote a new post on the company blog about MySQL's cool ST_Distance_Sphere function.

On a client project recently, we had to make it easy to filter database query results based on the distance between a user and an entity in our database. It's easy to get overwhelmed in that context, worrying about the crazy amount of PHP calculations you're going to have to run. ... If you need to calculate this, you can actually get surprisingly far by just using MySQL!

https://tighten.co/blog/a-mysql-distance-function-you-should-know-about