detecting whether some records are excluded from an INSERT INTO operation - sql

Question

I have a composite primary key on 2 columns in the table I am INSERTing into. I come from working with SQL Server, and I know that if I attempted to insert a duplicate key value into a PK table, it would throw an error.
My problem is, my code is not throwing this kind of error. Can you look at it and see if it's a problem with the code? Or does Access not throw errors for this kind of violation?
[Edit]
I guess I'm looking for a way to just acknowledge that duplicate records are attempted to be inserted. I want the current functionality to remain (dups are tossed; valid records are inserted). I don't want the entire INSERT to get rolled back.
My code is below.
Function InsertData(Ignore As String)
' define file path of CSV to be imported
Dim CurrentDate As String
Dim CurrentYear As String
CurrentDate = Format(Date, "yyyymmdd")
CurrentYear = Format(Date, "yyyy")
Dim Exfile As String
Exfile = iPath + "\" + CurrentYear + "\" + "FileName" + CurrentDate + ".txt"
'this calls a saved import routine
DoCmd.RunSavedImportExport "tbl_TEMP"
'merge data with that already existing in tbl_Perm.
'the clustered PK on product_ID and As_of_Date prevents dup insertion
Dim dbs As Database
Dim errLoop As Error
Set dbs = OpenDatabase(iPath + "\ExDatabase.mdb")
dbs.Execute " INSERT INTO tbl_Perm (Col1,Col2,Date_Created) " _
& "SELECT ColA + ColB, ColC, Format$(Now(),'Short Date')" _
& "FROM tbl_TEMP;"
' Trap for errors, checking the Errors collection if necessary.
On Error GoTo Err_Execute
'delete temp table
dbs.Execute "DROP TABLE tbl_TEMP;"
dbs.Close
Err_Execute:
' Notify user of any errors that result from
' executing the query.
If DBEngine.Errors.Count > 0 Then
For Each errLoop In DBEngine.Errors
MsgBox "Error number: " & errLoop.Number & vbCr & _
errLoop.Description
Next errLoop
End If
Resume Next
End Function

Answer 1

From the Microsoft DAO Doc (here):
In a Microsoft Access workspace, if you provide a syntactically
correct SQL statement and have the appropriate permissions, the
Execute method won't fail — even if not a single row can be modified
or deleted. Therefore, always use the dbFailOnError option when using
the Execute method to run an update or delete query. This option
generates a run-time error and rolls back all successful changes if
any of the records affected are locked and can't be updated or
deleted.
So add the dbFailOnError option to your call.

Answer 2

If you want to allow the INSERT to proceed and determine whether any duplicates were rejected then you could do something like this
Dim cdb As DAO.Database, qdf As DAO.QueryDef, rst As DAO.Recordset
Dim sqlSelect As String, sourceRecords As Long
Set cdb = CurrentDb
sqlSelect = _
"SELECT ColA + ColB, ColC, Format$(Now(),'Short Date') " & _
"FROM tbl_TEMP"
Set rst = cdb.OpenRecordset("SELECT COUNT(*) AS n FROM (" & sqlSelect & ")", dbOpenSnapshot)
sourceRecords = rst!n
rst.Close
Set rst = Nothing
Set qdf = cdb.CreateQueryDef("", _
"INSERT INTO tbl_Perm (Col1,Col2,Date_Created) " & sqlSelect)
qdf.Execute
If qdf.RecordsAffected < sourceRecords Then
Debug.Print sourceRecords - qdf.RecordsAffected & " record(s) not inserted"
End If
Set qdf = Nothing
Set cdb = Nothing

Answer 3

The line
On Error GoTo Err_Execute
is after you execute your SQL statement. The Err_Execute block will - in this case - be called every time because there is not statement like Exit Function before the label. I am not sure what happens to the errors if you close the connection before evaluating the error collection.