“No current record” after Cancel in combo_BeforeUpdate
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29-09-2019 - |
문제
I'm trying to prevent circular (or even cascading) references in my data, and it seems it's only working part of the time.
In Access 2007, I have the following table:
create table mfr (
mfr_id Autonumber,
mfr_nm Text(255),
mfr_is_alias_for_id Long Integer
)
I'm importing a bunch of data from Excel, and the mfr_nm is one of the columns from the worksheet. I can't control how data gets entered into Excel, so I want a way of capturing alternate spellings as being "really" same thing. So far, so good (I think...).
Now I've built a form off of this table. I've got a ComboBox for the alias--again, so far, so good. However, when I add this code to the BeforeUpdate event, things get "interesting" (error handling omitted):
If Not IsNull(cboMfrAlias) Then
If Not IsNull(DLookup("mfr_is_alias_for_id", "mfr", "mfr_id=" & cboMfrAlias)) Then
MsgBox """Alias for"" must not also be an alias.", vbExclamation
Cancel = True
End If
End If
This works exactly as I expect it to when the form is in Form View, but if I'm in Datasheet View my MsgBox is immediately followed by an Access-generated "No current record" error that is not caught by error handling within the BeforeUpdate sub.
Can I catch this error? Where?
해결책
Your dropdown list should filter out entries that are aliases. In other words, don't display a choice the user can't make.
You'd do this by simply eliminating from the dropdown the choices where mfr_is_alias_for_id Is Not Null.
I've implemented this in various guises and it works fine.
다른 팁
I'm addressing the "No Current Record" error part of your question, from so long ago. After checking google for an answer, I found this link which was helpful. However, instead of using NZ() to transform the troublesome binary field in an aggregate query, I used troublesomefield: IIF([troublesomefield] IS NULL,NULL,[troublesomefield])
and this worked to banish the error. So my solution is only a small variation on the original answer I found, but it gets around the error and let you keep nulls if you want to...