Distance on earth calculation in SQL

Here's how to create an SQL function to calculate the distance (in KM) between to points on earth. This is an estimation since the distance is calculated as if the earth was round, but it's close enough for most purposes:

CREATE FUNCTION dist (@latFrom float, @longFrom float,@latTo float, @longTo float)
        RETURNS float
AS
BEGIN
        DECLARE @Distance float
        SET @Distance =
                (SIN(RADIANS(@latFrom)) *
                SIN(RADIANS(@latTo)) +
                COS(RADIANS(@latFrom)) *
                COS(RADIANS(@latTo)) *
               
                COS(RADIANS(@longFrom - @longTo)))
 
        SET @Distance = (DEGREES(ACOS(@Distance))) * 69.09 * 1.609344
       
        RETURN(@Distance)
END