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        string speicherdatei, speicherurl;
            SaveFileDialog sfd = new SaveFileDialog();
            sfd.ShowDialog();
            speicherdatei = sfd.FileName;
            speicherurl = sfd.InitialDirectory;

            if (speicherdatei == "")
            {
                MessageBox.Show("Sie haben keine Datei gewählt!");
                return;
            }
            
            OleDbConnection con = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source="+speicherurl+speicherdatei);
            string tabellenname = textBox1.Text+"_neu";
           
            StringBuilder sb = new StringBuilder();
            sb.Append("CREATE TABLE ");
            sb.Append(tabellenname);
            sb.Append("(");
            for (int i = 0; i < dt2.Columns.Count; i++)
            {
                sb.AppendFormat("{0} {1},", dt2.Columns[i].ColumnName, dt2.Columns[i].DataType.ToString());
            }
            sb.Append(")");
            sb.Replace(",)", ")");
            sb.Replace("System.", "");

            OleDbCommand cmd = new OleDbCommand(sb.ToString(), con);
            con.Open();
            cmd.ExecuteNonQuery();
            con.Close();
            

            OleDbDataAdapter dadapter2 = new OleDbDataAdapter();
            dadapter2.SelectCommand = new OleDbCommand("Select * from " + tabellenname, con);
            OleDbCommandBuilder custCB = new OleDbCommandBuilder(dadapter2);

            dadapter2.Update(dt2);                    

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cmd.ExecuteNonQuery();