计算经纬度之间距离

传递两个经纬度，计算中间的距离，单位km

USE [Witbank_Times]
GO
/****** Object:  UserDefinedFunction [dbo].[fnGetDistance]    Script Date: 2016/9/9 15:23:10 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:        <gaoxing>
-- Create date: <2015-09-22>
-- Description:    <计算两个经纬度之间的距离>
-- =============================================
--创建经纬度距离计算函数
 ALTER FUNCTION [dbo].[fnGetDistance] 
 --LatBegin 开始经度
 --LngBegin 开始维度
(@LatBegin float, @LngBegin float, @LatEnd float, @LngEnd float)  RETURNS FLOAT
       AS
BEGIN
       --距离(千米)
       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 Round(@Distance,2)
END