我可以选择MySQL的哪些行与目标坐标相距<x英里？ （mysql邻近搜索）

Question

There's a few questions like this on Stack Overflow but because i can't find any quite similar enough for me to follow.

I'm looking to select rows from db which are within x miles of a target.

example table columns:

| city_name(varchar) | lat(decimal) | lon(decimal) |

query effect i'm looking for (either using php or mysql)

$target_lat = ;
$target_lon = ;
"SELECT table.city_name WHERE (table.lat,table.lon) LESS THAN 20 MILES FROM ($target_lat,$target_lon")

obviously i don't expect query to take this structure! (i've never used Pi etc in mysql...)

Answer 1

I found this which is brilliant and really easy to understand

http://code.google.com/apis/maps/articles/phpsqlsearch.html