Filter on distance from a town or zipcode?

[lostrisq]

I am wondering.... For one of my clients I need to create a site which contains a vacancy database.

The catalog module is off course very suitable for creating this.

But.... I would like visitors to be able to search/sort vacancies by entering their postcode or town and the choose the amount of miles/kilometers around it. (Like this site: http://www.randstad.nl

Is it possible to achieve this with the catalog module?

[ramjet]

I don't know anything re catalog, but would like to point out that neither a town nor a zipcode are a point, so really they cannot be searched around (you CAN search around their centre - which is a point).

To search WITHIN a zipcode or a town you would just need to store the zip and town fields of each accommodation entry.
To search AROUND a point (eg: an address), you would need to the store latitude and longitude values fields of each accommodation entry.
To search AROUND the central point of a zip or town, I think you would need to store the lat and long values of those central points in a seperate table, retrieve them then compare with the lat/long of all your accommodation entries.

A formula called the Haversine formula can be used to compute great-circle distances between two pairs of coordinates on a sphere.

From http://code.google.com/apis/maps/art...ml#findnearsql

Here's the SQL statement that will find the closest 20 locations that are within a radius of 25 miles to the 37, -122 coordinate. It calculates the distance based on the latitude/longitude of that row and the target latitude/longitude, and then asks for only rows where the distance value is less than 25, orders the whole query by distance, and limits it to 20 results. To search by kilometers instead of miles, replace 3959 with 6371.

SELECT id, ( 3959 * acos( cos( radians(37) ) * cos( radians( lat ) ) * cos( radians( lng ) - radians(-122) ) + sin( radians(37) ) * sin( radians( lat ) ) ) ) AS distance FROM markers HAVING distance < 25 ORDER BY distance LIMIT 0 , 20;

Hope this helps

[lostrisq]

Hey Ramjet!

Thank you so much for your answer....

I have to really really think about what you wrote... :-)
point taken, but i wonder whether i can realize this myself.