//一个数据访问层的例子，该类并不需要从数据库中检索数据，
    //只是删除库表中的一些记录，或添加一些记录，请帮忙优化，或指出不足
    class DataAccess
    {
        private OleDbConnection Conn;
        private OleDbDataAdapter DALab;
        private DataTable tblRawData;
        
        public DataAccess(string strconn)
        {
            Conn = new OleDbConnection(strconn);
            Conn.Open();
            DALab = new OleDbDataAdapter("select * from lab_rawdata", Conn);
            tblRawData = new DataTable("lab_rawdata");
            DALab.FillSchema(tblRawData, SchemaType.Source);//并不需要检索记录
            Conn.Close();
        }

        public void AddNew(string Sample,string Item,decimal Result)
        {
            DataRow drCurrent = tblRawData.NewRow();
            drCurrent["sample_id"] = Sample;
            drCurrent["item_code"] = Item;
            drCurrent["result"] = Result;
            tblRawData.Rows.Add(drCurrent); 
        }

        public void DelRows(string Sample)
        {
            Conn.Open();
            string strDel = "delete from lab_rawdata where sample_id = " + Sample;
            OleDbCommand mycommand = new OleDbCommand(strDel, Conn);
            mycommand.ExecuteNonQuery();
            Conn.Close();
        }

        public void UpDate()
        {
            DALab.Update(tblRawData );
            tblRawData.Clear();
            tblRawData.AcceptChanges();
        }
    }