My zipcode query is not returning the correct results

[Reessee]

The following query:

CREATE PROCEDURE GetDistance AS
 
SELECT a.ZIPCODE, a.CITY, a.STATE,
ROUND(
(ACOS(
(SIN(c.LATITUDE) * SIN(a.LATITUDE)) +
(COS(c.LATITUDE) * COS(a.LATITUDE) *
COS(a.LONGITUDE - c.LONGITUDE))
)
)
* 3963,1
) AS distance
FROM Zipcodes a, Zipcodes c
WHERE (
ACOS(
(SIN(c.LATITUDE) * SIN(a.LATITUDE)) +
(COS(c.LATITUDE) * COS(a.LATITUDE) * COS(a.LONGITUDE - c.LONGITUDE))
)
) * 3963 <= '10'
AND c.ZIPCODE='80222'
ORDER BY distance
GO

tells me that the only zipcode within 10 miles of 80222 is 80222 and if I replace 10 with 25 it offers only one additional zip code? Does anyone have any ideas why this might be happening?
Thanks so much for any suggestions anyone has to offer.:rolleyes:

[campkev]

give us table setup and what data you have in those tables

[Reessee]

Column Name Data Type
ZIPCODE nvarchar
LATITUDE float
LONGITUDE float
CITY nvarchar
STATE nvarchar
ABBR nvarchar

The first five entries look like this:
00501 40.81718 -73.04536 HOLTSVILLE NEW YORK NY
00544 40.81718 -73.04536 HOLTSVILLE NEW YORK NY
00601 18.165273 -66.722583 ADJUNTAS PUERTO RICO PR
00602 18.393103 -67.180953 AGUADA PUERTO RICO PR
00603 18.455913 -67.14578 AGUADILLA PUERTO RICO PR

I think that my problem may be that I am assuming that the latitude and longitude are in radins. But they may be in degrees and I do not know how to tell the difference.

Have I provided enough information?

[campkev]

yes, those locations are in degrees

[Reessee]

Thank you for your help.

[ashley1213]

May be something is wrong with your formula or data. The both you can find on Zip Postal Codes web site for example.

[campkev]

May be something is wrong with your formula or data. The both you can find on Zip Postal Codes web site for example.

While I don't want to discourage new members, you might want to look at the dates of previous messages. This thread has been dead for 2 and a half years.