[SQL] Distanza tra due punti geografici

sp TSQL che dati 2 punti geografici (latitudine e longitutide) ritorna la loro distanza in miglia:


ALTER FUNCTION dbo.udfComputeDistance(
 @lat1 float,
@lon1 float,
@lat2 float,
@lon2 float)

RETURNS float
AS

begin
declare @rt float
if @lat2=0 and @lon2=0

begin

set @rt=1000000

end

else

begin

 -- dLong represents the differences in longitudes

-- while dLat is the difference in latitudes

declare @dLong float
declare @dLat float
declare @temp float

-- Convert the decimal degrees to radians

set @lat2 = radians(@lat2)

set @lon1 = radians(@lon1)

set @lat1 = radians(@lat1)

set @lon2 = radians(@lon2)

-- Compute the degree differences

set @dLong = @lon2 - @lon1

set @dLat = @lat1 - @lat2

-- Compute the first part of the equation

set @temp = (square(sin(@dLat/2.0))) + cos(@lat2) * cos(@lat1) * (square(sin(@dLong/2.0)))

-- Return the approximate distance in miles

-- Note that 3956 is the approximate median radius of the Earth.

set @rt=(2.0 * atn2(sqrt(@temp), sqrt(1.0-@temp)))*3956.0

end

return @rt

end

 

 

 

 

 

 

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