InfoPath will generate a new sequential value (Unique ID) based upon a user-selected value

Question

I am trying to create an Infotpath form that is submitted to SharePoint and I have it working but not the way I would like it to work. Any help with much needed detail would be greatly appreciated due to the fact I am still a "newbie".
I have two fields one called Ref Number which is a read only text box to the users and another field called Own Info which is a Drop-Down list. Bascially I would like it to where when the user clicks the submit button the Ref Number will get incremented.
I have the form incrementing with leading zeros but every time the submit button is clicked and I would like it to be determined by the Own Info and not like this : concat(Own_Info , "-", substring("000", 1, 4 - string-length(max(ID) +
1)), max(ID) + 1).
Example:
1.Own Info: D652 Ref Number : D652-0001
2.Own Info: D652 Ref Number: D652-0002
3.Own Info: D653 Ref Number : D653-0001
4.Own Info: D653 Ref Number : D653-0002
5.Own Info: D652 Ref Number : D652-0003
So the Ref Number increments based off of the Own Info which will be about 25 different options. Again any help with much needed detail would be greatly appreciated. Thanks in advance!!!! 

Answer 1

I have also done something like this using a list for the next reference number:
Set up a list with the Own Info number and Next Ref Number
Populate the list with the possible Own Info Numbers and the next available ref number for each one
Own Info | Next Ref Number
D652      |    0004
D653      |    0003
Use a workflow when the submit button is clicked that looks up the Own Info number from your custom list and gets the next ref number that corresponds to it
concatenate the two and use for the combined number
use the same workflow to update the next ref number
One thing to be wary of when you set something up like this, is that if the workflow will run often (the form is being used and submitted heavily) a race condition can exist where two workflows might try to update the same Own Info->Next Ref Number. This
is probably not the solution to use if this is your scenario.
Marlene Lanphier MCTS