'....
Dim con As New OleDb.OleDbConnection
    Dim cmd As New OleDb.OleDbCommand
'....
Private Sub dgvLaden()
 
        cmd.CommandText = "select * from T_Rechnungen"
 
        Dim a As New OleDb.OleDbDataAdapter(cmd.CommandText, con)
        Dim t As New DataTable
 
        Try
            con.Open()
            a.Fill(t)
            con.Close()
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
        DataGridView1.DataSource = t
end sub

private sub DBupdate
 
cmd.CommandText = "update T_Rechnungen"
        Dim a As New OleDb.OleDbDataAdapter(cmd.CommandText, con)
        Dim t As New DataTable
 
        Try
            con.Open()
            a.Update(t)
            con.Close()
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
end sub

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Woher soll ich wissen was ich denke, bevor ich h?re was ich sage?