Query to return only most recent unique values

[ruf7109]

I read through some of the other unique value posts and none seem to fit my needs. I am a bit new to Access, I think I have a decent grasp, but there is a lot to learn.

I have a set of devices that are assigned to a truck, on occastion they are moved from truck to truck, I need to be able to track where they are AND where they have been. Here is what I have:



ID (autonumber)
GPS ID (number, this is the specific ID to each device)
Truck Number (this is the specific ID for each truck
Installation Date (Date installed / moved)

I have created a query to show the data I need, I have put them in order based on date.

- I must keep each event stored on the table

Goal:

To show a list of the current location of each device, nothing more.

Thank you for your help!

[orange]

I think readers would like to know more about this part

they are moved from truck to truck

How, when, why, by whom? I think this is key to tracking.

For clarity, you are interested in the location(s) of the devices or the trucks or both?
I asked because if you want to know which truck has which device, I don't see the need for GPS.
I do recognize you have said GPSID, so it is device, but I'm a little confused with

where they have been

.

[ItsMe]

Whoever is in charge of assigning a device to a truck would update a table that had

tblGPSAssignment
GPSAssignmentID (Autonumber)
GPSID (Long)
TruckID (Long)
UserID (Long)
AssignmentDate (Date)
...

[ruf7109]

The devices are GPS devices. So I need to know which GPS device is on which truck at this time. So I want to limit my query results to only recent unique values.

[June7]

For one method, review http://allenbrowne.com/subquery-01.html#TopN

Other methods would involve aggregate query or domain aggregate functions.

[orange]

ruf7109,

Did you see ItsMe's post -- the event where the devices change trucks is where you want to capture and record information. How many you may want to display is a separate issue.