STDistance (geography Data Type)
Returns the shortest distance between a point in a geography instance and a point in another geography instance.
.STDistance ( other_geography )
Is another geography instance from which to measure the distance between the instance on which STDistance() is invoked. If other_geography is an empty set, STDistance() returns null.
SQL Server return type: float
CLR return type: SqlDouble
STDistance() always returns null if the spatial reference IDs (SRIDs) of the geography instances do not match.
The following example finds the distance between two geography instances.
DECLARE @g geography; DECLARE @h geography; SET @g = geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326); SET @h = geography::STGeomFromText('POINT(-122.34900 47.65100)', 4326); SELECT @g.STDistance(@h);