conn.Open();                  
                    OleDbDataAdapter Bada = new OleDbDataAdapter("select * from " + cmdText, conn);//建立一个DataAdapter对象
                    OleDbCommandBuilder cb = new OleDbCommandBuilder(Bada);//这里的CommandBuilder对象一定不要忘了,一般就是写在DataAdapter定义的后面
                    cb.QuotePrefix = "[";
                    cb.QuoteSuffix = "]";
                    DataSet ds = new DataSet();//建立DataSet对象
                    Bada.Fill(ds, "demo");//填充DataSet
                    DataTable dt = ds.Tables["demo"];//建立一个DataTable对象，方便操作
                    foreach (DataRow tempRow in dt1.Rows)
                    {
                        DataRow dr = dt.NewRow();
                        dr.ItemArray = tempRow.ItemArray;//行复制
                        dt.Rows.Add(dr);
                    }
                    Bada.Update(ds, "demo");//用DataAdapter的Update()方法进行数据库的更新