private HocKi GetDataFromDataRow(DataTable dt, int i)
 {
     HocKi HK = new HocKi();
     HK.MaHocKi = Convert.ToInt32(dt.Rows[i]["maHocKi"].ToString());
     HK.TenHocKi = dt.Rows[i]["tenHocKi"].ToString();
     return HK;
 }
 public HocKi[] getAllHK()
 {
     string strSql = "SELECT * FROM HocKi";
     DataTable dt = DataProvider.executeQuery(strSql);
     int n = dt.Rows.Count;
     HocKi[] allClass = new HocKi[n];
     for (int i = 0; i < n; i++)
     {
         HocKi TK = GetDataFromDataRow(dt, i);
         allClass[i] = TK;
     }
     return allClass;
 }