从别的地方烤过来的，自己试了一下，可以计算 出来，不过正确不正确的就不太懂了。
USE [niaoren]
GO
/****** Object: UserDefinedFunction [dbo].[fnGetDistance] Script Date: 2017/7/28 星期五 12:17:56 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
--计算地球上两个坐标点（经度，纬度）之间距离sql函数
--作者：lordbaby
--整理：www.aspbc.com
ALTER FUNCTION [dbo].[fnGetDistance](@LatBegin REAL, @LngBegin REAL, @LatEnd REAL, @LngEnd REAL) RETURNS FLOAT
AS
BEGIN
--距离(千米)
DECLARE @Distance REAL
DECLARE @EARTH_RADIUS REAL
SET @EARTH_RADIUS = 6378.137 --地球半径
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
RETURN @Distance
END
