Die Methoden MoveFirst, MoveLast, MoveNext und MovePrevious – Beispiel (VB)

In diesem Beispiel werden die Methoden MoveFirst, MoveLast, MoveNext und MovePrevious verwendet, um den Datensatzzeiger eines Recordset basierend auf dem angegebenen Befehl zu verschieben. Die MoveAny-Prozedur ist erforderlich, damit diese Prozedur ausgeführt werden kann.

'BeginMoveFirstVB  
  
    'To integrate this code  
    'replace the data source and initial catalog values  
    'in the connection string  
  
Public Sub Main()  
    On Error GoTo ErrorHandler  
  
    ' connection and recordset variables  
    Dim rstAuthors As ADODB.Recordset  
    Dim Cnxn As ADODB.Connection  
    Dim strCnxn As String  
    Dim strSQLAuthors  
     ' record variables  
    Dim strMessage As String  
    Dim intCommand As Integer  
  
    ' Open connection  
    Set Cnxn = New ADODB.Connection  
    strCnxn = "Provider='sqloledb';Data Source='MySqlServer';" & _  
        "Initial Catalog='Pubs';Integrated Security='SSPI';"  
    Cnxn.Open strCnxn  
  
    ' Open recordset from Authors table  
    Set rstAuthors = New ADODB.Recordset  
    rstAuthors.CursorLocation = adUseClient  
    ' Use client cursor to enable AbsolutePosition property  
    strSQLAuthors = "Authors"  
    rstAuthors.Open strSQLAuthors, Cnxn, adOpenStatic, adLockReadOnly, adCmdTable  
  
    ' Show current record information and get user's method choice  
    Do  
        strMessage = "Name: " & rstAuthors!au_fname & " " & _  
            rstAuthors!au_lname & vbCr & "Record " & _  
            rstAuthors.AbsolutePosition & " of " & _  
            rstAuthors.RecordCount & vbCr & vbCr & _  
            "[1 - MoveFirst, 2 - MoveLast, " & vbCr & _  
            "3 - MoveNext, 4 - MovePrevious]"  
        intCommand = Val(Left(InputBox(strMessage), 1))  
  
         ' for exiting the loop  
        If intCommand < 1 Or intCommand > 4 Then  
            MsgBox "You either entered a non-number or canceled the input box. Exit the application."  
            Exit Do  
        End If  
  
        ' Use specified method while trapping for BOF and EOF  
        Select Case intCommand  
            Case 1  
                rstAuthors.MoveFirst  
            Case 2  
                rstAuthors.MoveLast  
            Case 3  
                rstAuthors.MoveNext  
                If rstAuthors.EOF Then  
                    MsgBox "Already at end of recordset!"  
                    rstAuthors.MoveLast  
                End If  
            Case 4  
                rstAuthors.MovePrevious  
                If rstAuthors.BOF Then  
                    MsgBox "Already at beginning of recordset!"  
                    rstAuthors.MoveFirst  
                End If  
        End Select  
    Loop  
  
    ' clean up  
    rstAuthors.Close  
    Cnxn.Close  
    Set rstAuthors = Nothing  
    Set Cnxn = Nothing  
    Exit Sub  
  
ErrorHandler:  
    ' clean up  
    If Not rstAuthors Is Nothing Then  
        If rstAuthors.State = adStateOpen Then rstAuthors.Close  
    End If  
    Set rstAuthors = Nothing  
  
    If Not Cnxn Is Nothing Then  
        If Cnxn.State = adStateOpen Then Cnxn.Close  
    End If  
    Set Cnxn = Nothing  
  
    If Err <> 0 Then  
        MsgBox Err.Source & "-->" & Err.Description, , "Error"  
    End If  
End Sub  
  
'EndMoveFirstVB  

Weitere Informationen

MoveFirst-, MoveLast-, MoveNext- und MovePrevious-Methode (ADO)
Recordset-Objekt (ADO)