Imports System.Data.SqlClient
..
Dim attDB As String = Application.StartupPath & "\Data" 
AppDomain.CurrentDomain.SetData("DataDirectory", attDB)
Dim con As SqlConnection = New SqlConnection( _
            "Data Source= (local);AttachDBFilename=|DataDirectory|\meineDB.mdf;" & _
            "Integrated Security= True; User Instance =True")
 
 
Try
  con.Open()
  MsgBox("Verbindung erfolgreich")
Catch ex As Exception
  MsgBox(ex.Message)
Finally
  con.Close()
End Try
...