Imports System.Linq
Imports System.Data.OleDb
 
Private Const MYCONSTR As String = _
  "Provider=MSDAORA.1;Password=#XXXXxxxXX#;User ID=ICH;Data" & _
  "Source=R2wehee3.zz008.Andi_bln_net.net;Persist Security Info=True;"
 
    Private Const TBL_NAME = "abcd.efgh_ijk_data"
 
    Public Function ConnectToOraDB() As DataTable
        Dim DTbl As DataTable, ConStr As String, OCmd As OleDbCommand, Adpt As _
          OleDbDataAdapter, ODbConn As OleDbConnection, Ds As New DataSet
        ODbConn = New OleDb.OleDbConnection(MYCONSTR)
        Try
            ODbConn.Open()
            ConStr = String.Format("SELECT * FROM " & TBL_NAME)
            OCmd = New OleDbCommand(ConStr, ODbConn)
            Adpt = New OleDbDataAdapter(OCmd)
 
            ' Hier kommt der Fehler OLEDBException  unbekannter fehler  Der 
            ' Datentyp wird nicht    
            ' unterstützt
            Adpt.Fill(Ds, TBL_NAME)
            DTbl = Ds.Tables.Item(TBL_NAME)
            ODbConn.Close()
 
            Return DTbl
                    Catch ex As Exception
            ODbConn.Close()
            Return Nothing
        End Try
    End Function

Der Weg ist weit und steinig .. (