automatically create primary key by concatonation?

In my table tblLandLocations I want to create a field that I would use as a
primary key, but that takes information entered into other fields and then
concatonates them into a string which I would then use as a primary key. I'm
not sure if this is even possible, since each record would need to refer to
itself to create the entry for the primary key field.

Example. Three fields: [LandownerID], [LandLocation], [ManagementUnit]
In my form, the user chooses the landowner by name from a combo box, and the
LandownerID (an autonumber) is stored in this table. They enter a new
information for [LandLocation] and [ManagementUnit]. What I want, is to
create an unique identifier from this, say
LandLocationID: [LandownerID] & "_" & [LandLocation] & "_" [ManagementUnit]
This would then serve as a primary key (or at the very least, just another
field but with no duplicates allowed) to check that no land locations per
landowner and management unit have been entered more than once. Is this
possible? Or would I have to use a query to concatonate the strings, and go
from there? (and where do I go from there?)
Thanks for any help, I hope it's not too confusing!

Sienna

Step back for a second...

If you are saying that you have (?3) fields that, taken together, provide
unique identification for each row, then you DON'T need to save all three a
second time ("concatenated into a string") just to use them as a unique
identification.

Instead, in design view, highlight all three fields, then click the primary
key button to make the combination of the three your primary key.

Regards

Jeff Boyce
Microsoft Office/Access MVP


"Sienna" wrote in message
...
In my table tblLandLocations I want to create a field that I would use as
a
primary key, but that takes information entered into other fields and then
concatonates them into a string which I would then use as a primary key.
I'm
not sure if this is even possible, since each record would need to refer
to
itself to create the entry for the primary key field.

Example. Three fields: [LandownerID], [LandLocation], [ManagementUnit]
In my form, the user chooses the landowner by name from a combo box, and
the
LandownerID (an autonumber) is stored in this table. They enter a new
information for [LandLocation] and [ManagementUnit]. What I want, is to
create an unique identifier from this, say
LandLocationID: [LandownerID] & "_" & [LandLocation] & "_"
[ManagementUnit]
This would then serve as a primary key (or at the very least, just another
field but with no duplicates allowed) to check that no land locations per
landowner and management unit have been entered more than once. Is this
possible? Or would I have to use a query to concatonate the strings, and
go
from there? (and where do I go from there?)
Thanks for any help, I hope it's not too confusing!

On Fri, 5 Jun 2009 13:09:01 -0700, "Jeff Boyce"
wrote:

Instead, in design view, highlight all three fields, then click the primary
key button to make the combination of the three your primary key.

Or, instead of making a composite primary key, use an AutoNumber for
your primary key, and include these three fields in a unique index to
prevent duplicates.

Armen Stein
Microsoft Access MVP
www.JStreetTech.com