Sql zip code distance

Okay, below is the whole function. Here are some values and their results compared to zipfind. Note the strange behavior for and , and others had this same value too. Search for 10 mile radius of and get distance between zip codes This post is only concerned with the distance function part my results sample : zip code miles latitude longitude 0. I dont' understand this: How can these three zip code finding website have such drastically different results???

These results seem to be off too far to be accounted for with simple rounding errors and the like. Anyone know what's going on here? Joe Celko. Another thought is that if we want the for mailing purposes, you can get a table of zones for each zip code.

This discussion thread is closed Start new discussion. Similar topics PHP. Find Distance between two zip codes. Well, starting with SQL Server , it is possible to get the same result, with a lot less effort, following two simple steps In this post I will walk through things step by step. Something similar to the data available from Melissa Data. If you do not, the key here is to be able to obtain a latitude and longitude for each entry.

Now, the key to this is actually to modify the records that you are going to be searching on. For example, if I have a listing of customer addresses and I want to calculate distances between them, I would be modifying my customer information.

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Linked 0. Related This may be slightly off topic, but you can make some very easy restrictions to approximate mileage boundaries. If for example you want a 20 mile radius from a given point, simply calculate the distance in a cardinal direction North, East Here's the question How about MAX? If the earth was perfectly round, and a flat approximation was used, miles would give a 1 mile max error? It probably gets quadratically worse as the radius increases? I am working on the error approx I'd bet a lot that it's very much not a constant, because for small distances, spherical trig and flat-earth calculations would be almost exactly the same.

For large distances, the errors become greater. I've got to pack for a trip now, but I'll be back Monday nite. I hope Arnold Fribble takes a look at this to give us his 2cents. Arnold, from the second link I believe I read that you implemented something similar, but that you broke the world up into latitude rings and slightly altered the conditions for each ring. So basically, the error is not constant, but I would still like to know if you think that the conditions are still a reasonable approximation for quick filtering?

I think what I gather is that this would only work within areas that do not cross too many latitude lines.