选择POINT（）的100米半径内的所有点

Question

I have a table in a database with over a million geospatial points that we'll call 'flags' . I also have a feed of live 'vehicles' which report their latitude and longitude positions.

Every time a vehicle's position comes through I need to run code that does this:

Select all flags that are within a 100 metre radius of this vehicle's position.

Is this possible with SQL? If so how could I go about doing it?

Answer 1

Should be doable using the formula

(x-center_x)^2 + (y - center_y)^2 < radius^2

You have all the component parts to do

SELECT foo
  FROM point p
 WHERE (((p.x - vehicle.x) * (p.x - vehicle.x)) + ((p.y - vehicle.y) * (p.y - vehicle.y))) < 1000

Or somethign like that, I've taken a few syntax punts

Answer 2

Check these resources:

1. Selecting points within a bounding circle -- gives detailed information about optimal solution: select rectangular area and then filter out points that do not fall into the circle inside that square;
2. Select coordinates which fall within a radius of a central point? -- similar question on stackoverflow.