Re: zip code search within x miles

[Eamon Daly]

I don't think anyone's replied with an actual great circle
calculation. Here's our zipcode table, populated with data
from zipcodedownload.com (and note the index on zipcode,
latitude, and longitude:
CREATE TABLE `zipcodes` (
 `zipcode` char(5) NOT NULL default '',
 `zipcode_type` enum('S','P','U','M') NOT NULL default 'S',
 `city` char(45) NOT NULL default '',
 `city_type` enum('D','A','N') NOT NULL default 'D',
 `state` char(75) NOT NULL default '',
 `state_code` char(2) NOT NULL default '',
 `area_code` char(3) default NULL,
 `latitude` double(12,6) NOT NULL default '0.000000',
 `longitude` double(12,6) NOT NULL default '0.000000',
 KEY `city_state_code` (`zipcode`,`city`,`state_code`),
 KEY `position` (`zipcode`,`latitude`,`longitude`)
) TYPE=MyISAM
Here's the calculation to get zipcodes within 5 miles of
02134:
SELECT
b.zipcode, b.state,
(3956 * (2 * ASIN(SQRT(
POWER(SIN(((a.latitude-b.latitude)*0.017453293)/2),2) +
COS(a.latitude*0.017453293) *
COS(b.latitude*0.017453293) *
POWER(SIN(((a.longitude-b.longitude)*0.017453293)/2),2)
)))) AS distance
FROM zipcodes a, zipcodes b, zipcodes c
WHERE
a.zipcode = '02134' AND # <-- Your starting zipcode
a.zipcode = c.zipcode AND
(3956 * (2 * ASIN(SQRT(
POWER(SIN(((a.latitude-b.latitude)*0.017453293)/2),2) +
COS(a.latitude*0.017453293) *
COS(b.latitude*0.017453293) *
POWER(SIN(((a.longitude-b.longitude)*0.017453293)/2),2)
)))) <= 5 # <-- Your target radius
GROUP BY distance
Takes about half a second on our box. Here's the explain:
*************************** 1. row ***************************
       table: a
        type: ref
possible_keys: city_state_code,position,default_city
         key: position
     key_len: 5
         ref: const
        rows: 2
       Extra: Using where; Using index; Using temporary; Using filesort
*************************** 2. row ***************************
       table: c
        type: ref
possible_keys: city_state_code,position,default_city
         key: position
     key_len: 5
         ref: const
        rows: 2
       Extra: Using where; Using index
*************************** 3. row ***************************
       table: b
        type: ALL
possible_keys: NULL
         key: NULL
     key_len: NULL
         ref: NULL
        rows: 70443
       Extra: Using where
In case you're curious about the number of zipcodes:
mysql> select count(*), count(distinct zipcode) from zipcodes;
+----------+-------------------------+
| count(*) | count(distinct zipcode) |
+----------+-------------------------+
|    70443 |                   42471 |
+----------+-------------------------+
Can't take credit for the SQL, by the way; I'm pretty sure I
found it on Google.
____________________________________________________________
Eamon Daly

----- Original Message ----- 
From: "Scott Haneda" <[EMAIL PROTECTED]>
To: "MySql" <mysql@lists.mysql.com>
Sent: Friday, April 15, 2005 5:37 PM
Subject: zip code search within x miles


How are sites doing the search by zip and coming up with results within x
miles?  Is there some OSS zip code download that has been created for 
this?

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