Synchronisieren schreibt und liest mit dem Jet OLE DB-Provider und ADO

Const USE_SAME_CONNECTION = False

Sub MissedReadsDemo()
Dim conn1 As New ADODB.Connection
Dim conn2 As New ADODB.Connection
Dim rs As New ADODB.recordset
Dim strConnect As String
Dim i As Long

    ' Set up our connection string (requires a database named c:\db1.mdb).
    strConnect = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=c:\db1.mdb"

    ' Open connection 1 and drop and re-create test table.
    conn1.CursorLocation = adUseServer
    conn1.Open strConnect
    On Error Resume Next
    conn1.Execute "drop table tmpTest", , _
        adExecuteNoRecords + adCmdText
    On Error GoTo 0
    conn1.Execute "create table tmpTest (id long)", , _
        adExecuteNoRecords + adCmdText
    
    ' Close connection 1 to flush the creation of table tmpTest. 
    conn1.Close
    
    ' Now open connection 1 and connection 2.
    conn1.Open strConnect
    conn2.Open strConnect
    
    ' Insert 10 records using connection 1.
    For i = 1 To 10
        conn1.Execute "insert into tmpTest (id) values (1)", , _
            adExecuteNoRecords + adCmdText
    Next i
    
    ' Attempt to read records using second connection if
    ' USE_SAME_CONNECTION is set to False.
    If (USE_SAME_CONNECTION) Then
        Set rs = conn1.Execute("select * from tmpTest", , adCmdText)
    Else
        Set rs = conn2.Execute("select * from tmpTest", , adCmdText)
    End If
    
    ' Count records in our table (should be 10).
    i = 0
    While Not rs.EOF
        i = i + 1
        rs.MoveNext
    Wend
    rs.Close

    If (USE_SAME_CONNECTION) Then
        MsgBox "Read " & i & " records using same connection."
    Else
        MsgBox "Read " & i & " records using 2 different connections."
    End If
    
    conn1.Close
    conn2.Close

End Sub
				

Sub SyncReadDemo()
Dim conn1 As New ADODB.Connection
Dim conn2 As New ADODB.Connection
Dim rs As New ADODB.recordset
Dim JRO As New JRO.JetEngine
Dim strConnect As String
Dim i As Long

    ' Set up our connection string (requires a database named c:\db1.mdb).
    strConnect = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=c:\db1.mdb"

    ' Open connection 1 and drop and re-create test table.
    conn1.CursorLocation = adUseServer
    conn1.Open strConnect
    On Error Resume Next
    conn1.Execute "drop table tmpTest", , _
        adExecuteNoRecords + adCmdText
    On Error GoTo 0
    conn1.Execute "create table tmpTest (id long)", , _
        adExecuteNoRecords + adCmdText
    
    ' Close connection 1 to flush the creation of table tmpTest. 
    conn1.Close
    
    ' Now open connection 1 and connection 2.
    conn1.Open strConnect
    conn2.Open strConnect
    
    ' Insert 10 records using connection 1.
    ' Note we must perform all writes inside of a transaction.
    conn1.BeginTrans
    For i = 1 To 10
        conn1.Execute "insert into tmpTest (id) values (1)", , _
            adExecuteNoRecords + adCmdText
    Next i
    conn1.CommitTrans
    
    ' Refresh cache for reader connection.
    JRO.RefreshCache conn2
    Set rs = conn2.Execute("select * from tmpTest", , adCmdText)
    
    ' Count records in our table (should be 10).
    i = 0
    While Not rs.EOF
        i = i + 1
        rs.MoveNext
    Wend
    rs.Close

    MsgBox "Read " & i & " records using different connections."
    
    conn1.Close
    conn2.Close

End Sub