Here's the math I used in VFP using the lat/long of both endpoints to
determine the distance:
FUNCTION CalcDistance(StartingLat as Number, StartingLong as Number,
EndingLat as Number, EndingLong as Number) as Number
RETURN 3956 * 2 * ASIN(SQRT((SIN((StartingLat - EndingLat) * pi()/180
/ 2)**2) + COS(StartingLat * pi()/180) * COS(EndingLat * pi()/180) *
(SIN((StartingLong - EndingLong) * pi()/180 / 2)**2) ))
ENDFUNC && CalcDistance(StartingLat as Number, StartingLong as Number,
EndingLat as Number, EndingLong as Number) as Number
It's called from this code:
select distinct destination ;
from (;
select distinct f1.ccity as city_in, f1.cstatecode as state_in,
f1.czipcode as zip_in, ALLTRIM(f2.ccity) + ', ' + ALLTRIM(f2.cstatecode)
as destination, ;
f2.czipcode as zip_dest, this.CalcDistance(VAL(f1.clatitude),
VAL(f1.clongitude), VAL(f2.clatitude), VAL(f2.clongitude)) as Distance;
from lucounties f1, lucounties
f2;
where f1.ccity = pcCity and f1.cstatecode = pcState and
f1.ccitytype = 'D' AND f2.ccitytype = 'D' AND f1.czipcode <> f2.czipcode
;
having Distance <= piRadius;
) x1 ;
order by destination ;
INTO CURSOR (lcCursor)
fyi. Thanks for all who chimed in!
--Mike
On 2017-03-15 03:32, Alan Bourke wrote:
Yeah, as much location data as you can get (address, Zip, lat & long)
and the Google API.
--
Alan Bourke
alanpbourke (at) fastmail (dot) fm
On Wed, 15 Mar 2017, at 05:23 AM,
[email protected] wrote:
(to be done in VFP9SP2 existing app)
Customer need: to grab/query towns near a certain zip code or city
name, akin to like when you use an app where you're looking for a car
and say "show me matches within 50 miles." I'm thinking
latitude/longitude and google somehow, but I thought I'd poll the
community to see what you'd recommend.
Thanks!
--Mike
[excessive quoting removed by server]
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