根据经纬度计算地球上两点之间的距离的Sql Server函数

单位是千米。

ALTER FUNCTION dbo.fnGetDistance
(
	@LatBegin REAL
	, @LngBegin REAL
	, @LatEnd REAL
	, @LngEnd REAL
)
RETURNS FLOAT
AS
BEGIN
	DECLARE @Distance REAL
	DECLARE @EARTH_RADIUS REAL
	SET @EARTH_RADIUS = 6378.137
	
	DECLARE @RadLatBegin REAL, @RadLatEnd REAL, @RadLatDiff REAL, @RadLngDiff REAL
	SET @RadLatBegin = @LatBegin * PI() / 180.0
	SET @RadLatEnd = @LatEnd * PI() / 180.0
	SET @RadLatDiff = @RadLatBegin - @RadLatEnd
	SET @RadLngDiff = @LngBegin * PI() / 180.0 - @LngEnd * PI() / 180.0
	
	SET @Distance = 2 * ASIN(SQRT(POWER(Sin(@RadLatDiff / 2), 2) + COS(@RadLatBegin) * COS(@RadLatEnd) * POWER(SIN(@RadLngDiff/2),2)))
	SET @Distance = @Distance * @EARTH_RADIUS
	--SET @Distance = Round(@Distance * 10000) / 10000
	
	RETURN @Distance
END

源算法来自“http://www.cnblogs.com/Aricc/archive/2010/05/05/1727711.html”，我只是把它改成了Sql Server的函数。