Closest to coordinates script

Ok I am looking for a form type script. That I put X and Y and Z coordinates into and click submit. (the Y doesnt matter as it is elevation) And when you click submit it searches through the list of coordinates I have and finds the closest based on the X and Z and echos The closest spot is: Boston X Y Z
Once again the Y really doesnt matter for when comparing the user input to the list.

The list/database Id prefer not to do it in MySql as I dont know anything with yet. And idea? Anyone know of a command they can point me to?

Thanks in advance!

I would say your best bet would be to use mysql, and just store the X, Z values with their location in a table. Then just use a form to search for the co-odinates thats the closest match the co-ordinates searched and display the location.

Ok.... what command would I use to find something that is close to a value?