Clone-Methode – Beispiel (VB)
In diesem Beispiel wird die Clone-Methode verwendet, um Kopien eines Recordsets zu erstellen und dann den Datensatzzeiger jeder Kopie unabhängig zu positionieren.
'BeginCloneVB
'To integrate this code
'replace the data source and initial catalog values
'in the connection string
Public Sub Main()
On Error GoTo ErrorHandler
'recordset array and connection variables
Dim arstStores(1 To 3) As ADODB.Recordset
Dim Cnxn As ADODB.Connection
Dim strSQLStore As String
Dim strCnxn As String
'record variables
Dim intLoop As Integer
Dim strMessage As String
Dim strFind As String
' Open a connection
Set Cnxn = New ADODB.Connection
strCnxn = "Provider='sqloledb';Data Source='MySqlServer';" & _
"Initial Catalog='Pubs';Integrated Security='SSPI';"
Cnxn.Open strCnxn
' Open recordset as a static cursor type recordset
Set arstStores(1) = New ADODB.Recordset
strSQLStore = "SELECT stor_name FROM Stores ORDER BY stor_name"
arstStores(1).Open strSQLStore, strCnxn, adOpenStatic, adLockBatchOptimistic, adCmdText
' Create two clones of the original Recordset
Set arstStores(2) = arstStores(1).Clone
Set arstStores(3) = arstStores(1).Clone
' Loop through the array so that on each pass the user
' is searching a different copy of the same Recordset
Do
For intLoop = 1 To 3
' Ask for search string while showing where
' the current record pointer is for each Recordset
strMessage = _
"Recordsets from stores table:" & vbCr & _
" 1 - Original - Record pointer at " & arstStores(1)!stor_name & vbCr & _
" 2 - Clone - Record pointer at " & arstStores(2)!stor_name & vbCr & _
" 3 - Clone - Record pointer at " & arstStores(3)!stor_name & vbCr & _
"Enter search string for #" & intLoop & ":"
strFind = Trim(InputBox(strMessage))
' make sure something was entered, if not then EXIT loop
If strFind = "" Then Exit Do
' otherwise locate the record from the entered string
arstStores(intLoop).Filter = "stor_name = '" & strFind & "'"
'if there's no match, jump to the last record
If arstStores(intLoop).EOF Then
arstStores(intLoop).Filter = adFilterNone
arstStores(intLoop).MoveLast
Else
MsgBox "Found " & strFind
End If
Next intLoop
Loop
' clean up
arstStores(1).Close
arstStores(2).Close
arstStores(3).Close
Cnxn.Close
Set arstStores(1) = Nothing
Set arstStores(2) = Nothing
Set arstStores(3) = Nothing
Set Cnxn = Nothing
Exit Sub
ErrorHandler:
' clean up
If Not arstStores(1) Is Nothing Then
If arstStores(1).State = adStateOpen Then arstStores(1).Close
End If
Set arstStores(1) = Nothing
If Not arstStores(2) Is Nothing Then
If arstStores(2).State = adStateOpen Then arstStores(2).Close
End If
Set arstStores(2) = Nothing
If Not arstStores(3) Is Nothing Then
If arstStores(3).State = adStateOpen Then arstStores(3).Close
End If
Set arstStores(3) = 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
'EndCloneVB