Query - Records within a certain range

[joycek]

Hello,

I've been wrestling with this problem for a while now and any assistance would be greatly appreciated.

I have a single table containing flight data. Each record represents a single flight. What I'm attempting to do is count of pairs of flights that come within a certain range of each other. For simplicity sake, let's say that any flights A and flights B passing through Point X within a certain window of time (-15/+15 minutes) of each other are counted as a pair. Each record has a unique numeric key and all the neccessary information. Getting a table of all the possible matches is easy. The tricky part however, is that I only want to count each pair once. Is there any way this can be done with an SQL query?

I apologize in advance if this isn't specific enough. I would really appreciate any feedback whatsoever.

 

[JonyBravo]

Hi!

Check DCOUNT statment where can be used for something like this:

textbox=DCount("[fieldflights]", "tblflights", [fieldcity]=' " & txtcity & " ')
by example now: if you type london on txtcity it will count only the flights where on fieldcity is recorded London.

Hope this help.....

JonyBravo

 

[joycek]

The feedback is much appreciated. I'm not sure DCount would work in this case however. I'm essentially counting pairs of flights that are in danger of collision. eg: Flight A and Flight B are at "almost" the same place at the same time. "Almost" is determined if Flight A is at the location of Flight B (give or take a constant) within +/- 15 minutes of each other.

I think this will be very difficult to do. But if anyone has any ideas I'd greatly appreciate it.