As an amateur coder for some years I have generally used sub forms when dealing with linked tables to make the transfer of ID field from primary to sub nice and simple...
However in my latest project the main form is a continuous form with a list of delivery runs (Date, RunName, RunCompleted) etc... Linked to this primary table is a delivery list containing (SKU of product, Qty etc...). I use a simple Relationship between the two tables.
Now, On the main (RUNS) form at the end of each row is a button that opens the DELIVERIES form and displays all records with matching RUNID
This is fine for displaying pre-existing data but when I want to add new records I have been using the following code attached to the OnCurrent event:
Me.RunID = DLookup("[RunID]", "tbl_BCCRuns", "RunID = " & Forms![frm_BCC_Runs_list]![RunID])
I have also used:
Forms![frm_BCC_Deliveries].Controls![RunID] = Forms![tbl_BCCRuns].Controls![RunID]
(Note: above done from memory and exact code may be incorrect but that's not the problem at hand)
Now... Both these options give me what I need however...
I find that as I am working on the database, or if you open certain forms in the right order (a bug I need to identify and fix clearly) you can open the DELIVERIES form without the filter (to view all deliveries for arguments sake) and the top entry (usually the oldest record) suddenly adopts the RUNID of the selected record back in the main form.
Now, my question is this, and the answer may be a simple "no" and that's fine, I'll move on...
Is there a better way, a way I am not familiar with or just don't know about due to my inconsistent Access progress, to transfer ID's to a form without risking contamination from improper use? Or do I just have to bite the bullet and make sure that there is just no possible way for that to happen?
In effort to alleviate the issue, I have created a Display Only form for viewing the deliveries but there are still times when I need to access the live historical data to modify other fields without wanting to modify the RUNID.
Any pointers greatly appreciated...
Since you only want to pull the RunID if the form is on a new record row, do a check to verify this is a new record.
If Me.NewRecord Then
Me.RunID = DLookup("[RunID]", "tbl_BCCRuns", "RunID = " & Forms![frm_BCC_Runs_list]![RunID])
End If
Could also consider a technique to synchronize parent and child forms when both are subforms on a main form (the main form does not have to be bound) https://www.fmsinc.com/MicrosoftAccess/Forms/Synchronize/LinkedSubforms.asp