GEOGRAPHY_DISTANCE
This function takes in two geospatial objects and measures the shortest distance between them, in meters, using the standard metric for distance on a sphere.

Syntax
GEOGRAPHY_DISTANCE ( geo1, geo2 )
Arguments
geo1, geo2: any valid geospatial object or WKT string: path, point or polygon.
Return Type
A double. The measured distance, in meters.
Examples
SELECT b.name AS neighbor, -> ROUND(GEOGRAPHY_DISTANCE(a.shape, b.shape), 0) AS distance_from_border -> FROM neighborhoods a, neighborhoods b -> WHERE a.id = 2 -> ORDER BY 1; +---------------------+----------------------+ | neighbor | distance_from_border | +---------------------+----------------------+ | Probability Bay | 0 | | Lower Bound Valley | 0 | | Axiom Township | 0 | | Elegant Island | 1935 | | Upper Bound Hill | 5632 | | Big Endian | 9016 | | Little Endian | 17290 | | Isle Zero | 17163 | ...