try
            {
                System.Data.OleDb.OleDbConnection MyConnection;
                System.Data.OleDb.OleDbCommand myCommand = new System.Data.OleDb.OleDbCommand();
                string sql = null;

                MyConnection = new System.Data.OleDb.OleDbConnection(@"provider=Microsoft.ACE.OLEDB.12.0; Data Source=" + sFileXls + "; Extended Properties=\"Excel 12.0;HDR=No;\"");

                MyConnection.Open();
				...
                myCommand.Connection = MyConnection;

                    sql =   "INSERT INTO [Sheet1$] (F1, F2, F3, F4, F5, F6, F7) " +
                            "VALUES (" +
                            "'" + tableResult.Rows[iDatarow]["id1"].ToString() + "'" + "," +
                            "'" + tableResult.Rows[iDatarow]["id2"].ToString() + "'" + "," +
                            "'" + tableResult.Rows[iDatarow]["id3"].ToString() + "'" + "," +
                            "'" + tableResult.Rows[iDatarow]["id4"].ToString() + "'" + "," +
                            "'" + tableResult.Rows[iDatarow]["id5"].ToString() + "'" + "," +
                            "'" + tableResult.Rows[iDatarow]["id6"].ToString() + "'" + "," +
                            "'" + tableResult.Rows[iDatarow]["id7"].ToString() + "')";

                    myCommand.CommandText = sql;
                    myCommand.ExecuteNonQuery();

                }
               
                myCommand.CommandText = sql;
                myCommand.ExecuteNonQuery();

                MyConnection.Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }