Calculating circle distance in MySQL and Propel
Martynas Jusevicius today poted new post on his blog about great-circle distance caculation in MySQL and Propel.
Eventually the simple distance formula that I have blogged about turned out to be too inaccurate, even for locations within city bounds. I needed to use a formula to calculate great-circle distance which takes into account that the Earth is a sphere.
With his written sql examples he shows how you can store temproary variables in MySQL query and gives code witch process calculations.