获取经纬度之间的距离的SQL函数(转)

--获取经纬度之间的距离（单位：米）
CREATE    function dbo.GetDistance(@Lon1 float,@Lat1 float,@Lon2 float,@Lat2 float) returns float
as
begin
 declare @ret float;
 declare @r float;
 declare @A float;
 declare @B float;
 declare @RA float;
 declare @RB float;
 declare @RL1 float;
 declare @RL2 float;
 select @r = 6371138, @A = abs(@Lat1 - @Lat2), @B = abs(@Lon1 - @Lon2), @RA = @A * pi() / 180.0, @RB = @B * pi() / 180.0, @RL1 = @Lat1 * pi() / 180.0, @RL2 = @Lat2 * pi() / 180.0, @ret = cast(2 * @r * asin(sqrt(sin(@RA/2) * sin(@RA/2) + cos(@RL1) * cos(@RL2) * sin(@RB/2) * sin(@RB/2))) as decimal(8,0));
 return @ret
end