MS Access VBA – Automatic Creation of Unique Alphanumeric ID

ms accessms-access-2010vba

All the accounts in my database have a unique ID, that begins with the letter "G" (always), and has a 3 digit number following (e.g. "G026", "G123","G005","G999", etc.)

When a user is inputting new-account information through a form, I would like the unique ID to be auto-generated. So I would like a unique "G000" formatted number that is NOT already taken up in the list of users. I have tried a few things, but am having a lot of trouble getting it to work.

Does anybody have any ideas of a module I could implement? I'm thinking of making a module that generates these numbers, and calling this module in the "Default Value" field.

THANK YOU!!

Best Answer

This will work. There may be something more elegant but this should get you started.

 Public Function GetUID() As String
      GetUID = "G" & Right("000" + CStr((CInt(Right(DMax("[YourIDField]", "TableContainingField"), 3)) + 1)), 3)
 End Function

Related Solutions

Ms-access – Sorting Report entries on alphanumeric combination

Your tag says MS Access, if you are using Jet/ACE in MS Access, you can sort by a user defined function.

Very roughly

SQL

SELECT t.ID, t.SortHere, SortOrder([SortHere]) AS ToSort
FROM Table t
ORDER BY SortOrder([SortHere]);

Code

Function SortOrder(ToSort)

Part1 = Left(ToSort, 1)

For i = 2 To Len(ToSort)
    If Not IsNumeric(Mid(ToSort, i, 1)) Then
        Part2 = Part2 & Mid(ToSort, 2, i - 2)
        Part3 = Mid(ToSort, i, 1)
        Part4 = Mid(ToSort, i + 1)
        Exit For
    End If
Next

If Part2 = vbNullString Then
    Part2 = Mid(ToSort, 2)
End If

SortOrder = Part1 & Format(Part2, "0000") _
          & Part3 & Format(Part4, "0000")

End Function

I am sure you can come up with a better function with a little thought.

Ms-access – Create primary keys based upon higher-level entity in access

I think the difficultly lies in using the parent table as part of the sub-table's primary key. So long as you have a reference to the parent table, you can always generate a reference that combines Location+Room or Room+Rack. Otherwise the primary key will get too hard to update and you have bad primary key.

I can see two ways to tackle this depending on how many locations, rooms, racks you have. It depends on quantity for your interface.

Firstly, a schema...

tblLocation(locationID[PK++], locationReference)
tblRoom(roomID[PK++], keyLocation[tblLocation.locationID], roomNumber)
tblRack(rackID[PK++], keyRoom[tblRoom.roomID], rackReference)
tblDevice(deviceID[pk++], keyRack[tblRack.rackID], positionU, deviceLabel)

...tables for custom devices can extend tblDevice

Foreign keys in square brackets, PK++ means an auto increment primary key.

As you can see, a Location has many Rooms, a Room has many Racks, a Rack has many Devices.

I have made primary keys as auto IDs as I prefer them to be integers and there's less to think about should you change a location/room/rack reference.

Populate this with Locations, Rooms and Racks as appropriate.

Solution 1 :: Not a lot of racks

Have three drop downs on the form.
User chooses a location, you then select all the rooms of that location in the next combobox.
User then selects the room, you then fill the next combobox with the racks in the room.
User then fills in device details and U position (which you probably want to validate to make sure that you don't have anything allocated there.)

Solution 2 :: Lots of racks

Have a query similar to:

SELECT
    rackID,
    locationReference + '-' + roomReference + '-' + rackReference AS [Full Location]
FROM tblLocation
    INNER JOIN tblRoom
        ON tblLocation.locationID = tblRoom.keyLocation
    INNER JOIN tblRack
        ON tblRoom.roomID = tblRack.keyRoom
ORDER BY
    locationReference ASC,
    roomNumber ASC,
    rackReference ASC

To generate a list of Location-Room-Rack references.

ABC-101-A/1
ABC-101-A/1
ABC-101-A/2
ABC-101-A/2
ABC-105-B8
ABC-105-B8
FAY-208-X8
FAY-210-A9T
FAY-210-A9T
FAY-210-F4
NAT-410-78
NAT-410-78

User selects one, then fills in the information. List will be equal to the number of racks (which could get a bit excessive).

Advantages

If you move a rack (or racks) of equipment from one room to another, it's just a simple update query to update the database
If a location/room/rack reference changes, you only have one piece of data to update.

Further schema additions

I've used racks in the past, I simplified the schema but these are some additions that spring to mind.

Add rackSize to tblRack: the size in U's
Add sizeU to tblDevice: the size of the device in U's

You can then do further validation: if you have a 39U rack and somebody tries to put a 5U device in at location 38, you can throw an error (as U's 40-42 don't exist!). Also if somebody puts a 3U device in at location 10, and something is in location 11, you know it won't fit or they have not updated the details of the device that is no longer there!

You could also make some clever queries that would tell you how much space there is in your racks (and where). But that's beyond the scope of this question!

Hope this helps.