Microsoft Access Tips for Serious Users

Provided by Allen Browne

Set AutoNumbers to start from ...

Resetting an AutoNumber to 1 is easy: delete the records, and compact the database.

But how do you force an AutoNumber to start from a specified value? The trick is to import a record with one less than the desired number, and then delete it. The following sub performs that operation. For example, to force table "tblClient" to begin numbering from 7500, enter:

    Call SetAutoNumber("tblClient", 7500)

Sub SetAutoNumber(sTable As String, ByVal lNum As Long)
On Error GoTo Err_SetAutoNumber
    ' Purpose:      set the AutoNumber field in sTable to begin at lNum.
    ' Arguments:    sTable = name of table to modify.
    '               lNum = the number you wish to begin from.
    ' Sample use:   Call SetAutoNumber("tblInvoice", 1000)
    Dim db As DAO.Database      ' Current db.
    Dim tdf As DAO.TableDef     ' TableDef of sTable.
    Dim i As Integer            ' Loop counter
    Dim fld As DAO.Field        ' Field of sTable.
    Dim sFieldName As String    ' Name of the AutoNumber field.
    Dim vMaxID As Variant       ' Current Maximum AutoNumber value.
    Dim sSQL As String          ' Append/Delete query string.
    Dim sMsg As String          ' MsgBox string.

    lNum = lNum - 1             ' Assign to 1 less than desired value.

    ' Locate the auto-incrementing field for this table.
    Set db = CurrentDb()
    Set tdf = db.TableDefs(sTable)
    For i = 0 To tdf.Fields.Count - 1
        Set fld = tdf.Fields(i)
        If fld.Attributes And dbAutoIncrField Then
            sFieldName = fld.name
            Exit For
        End If
    Next

    If Len(sFieldName) = 0 Then
        sMsg = "No AutoNumber field found in table """ & sTable & """."
        MsgBox sMsg, vbInformation, "Cannot set AutoNumber"
    Else
        vMaxID = DMax(sFieldName, sTable)
        If IsNull(vMaxID) Then vMaxID = 0
        If vMaxID >= lNum Then
            sMsg = "Supply a larger number. """ & sTable & "." & _
                sFieldName & """ already contains the value " & vMaxID
            MsgBox sMsg, vbInformation, "Too low."
        Else
            ' Insert and delete the record.
            sSQL = "INSERT INTO " & sTable & " ([" & sFieldName & "]) SELECT " & lNum & " AS lNum;"
            db.Execute sSQL, dbFailOnError
            sSQL = "DELETE FROM " & sTable & " WHERE " & sFieldName & " = " & lNum & ";"
            db.Execute sSQL, dbFailOnError
        End If
    End If
Exit_SetAutoNumber:
    Exit Sub

Err_SetAutoNumber:
    MsgBox "Error " & Err.Number & ": " & Err.Description, , "SetAutoNumber()"
    Resume Exit_SetAutoNumber
End Sub