Home/ Questions/Q 6578791
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-25T15:48:59+00:00

Sorry for posting something that’s probably obvious, but I don’t have much database experience.

  • 0

Sorry for posting something that’s probably obvious, but I don’t have much database experience. Any help would be greatly appreciated – but remember, I’m a beginner 🙂

I have a table like this:
Table.fruit
ID type Xcoordinate Ycoordinate Taste Fruitiness
1 Apple 3 3 Good 1,5
2 Orange 5 4 Bad 2,9
3 Apple 7 77 Medium 1,4
4 Banana 4 69 Bad 9,5
5 Pear 9 15 Medium 0,1
6 Apple 3 38 Good -5,8
7 Apple 1 4 Good 3
8 Banana 15 99 Bad 6,8
9 Pear 298 18789 Medium 10,01
… … … … … …
1000 Apple 1344 1388 Bad 5
… … … … … …
1958 Banana 759 1239 Good 1
1959 Banana 3 4 Medium 5,2

I need:
A table that gives me

The n (eg.: n=5) closest points to EACH point in the original table, including distance
Table.5nearest (please note that the distances are fake). So the resulting table has ID1, ID2 and distance between ID1 and ID2 (can’t post images yet, unfortunately).

ID.Fruit1 ID.Fruit2 Distance
1 1959 1
1 7 2
1 2 2
1 5 30
1 14 50
2 1959 1
2 1 2
… … …
1000 1958 400
1000 Xxx Xxx
… … …

How can I do this (ideally with SQL/database management) or in ArcGis or similar? Any ideas?
Unfortunately, my table contains 15000 datasets, so the resulting table will have 75000 datasets if I choose n=5.
Any suggestions GREATLY appreciated.

EDIT:

Thank you very much for your comments and suggestions so far. Let me expand on it a little:
The first proposed method is sort of a brute-force scan of the whole table rendering huge filesizes or, likely, crashes, correct?
Now, the fruit is just a dummy, the real table contains a fix ID, nominal attributes (“fruit types” etc), X and Y spatial columns (in Gauss-Krueger) and some numeric attributes.
Now, I guess there is a way to code a “bounding box” into this, so the distances calculation is done for my point in question (let’s say 1) and every other point within a square with a certain edge length. I can imagine (remotely) coding or querying for that, but how do I get the script to do that for EVERY point in my ID column. The way I understand it, this should either create a “subtable” for each record/point in my “Table.Fruit” containing all points within the square around the record/point with a distance field added – or, one big new table (“Table.5nearest”). I hope this makes some kind of sense. Any ideas? THanks again

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    To get all the distances between all fruit is fairly straightforward. In Access SQL (although you may need to add parentheses everywhere to get it to work :P):

    select   fruit1.id,
         fruit2.id,
         sqr(((fruit2.xcoordinate - fruit1.xcoordinate)^2) + ((fruit2.ycoordinate - fruit1.ycoordinate)^2)) as distance
from     fruit as fruit1
join     fruit as fruit2
on       fruit2.id <> fruit1.id
order by distance;

    I don’t know if Access has the necessary sophistication to limit this to the “top n” records for each fruit; so this query, on your recordset, will return 225 million records (or, more likely, crash while trying)!

    • 0