编程|对象首先，我们要来定义一个数据库表，以保存舆论调查的想关数据，看下面这个表：
/*新闻调查表*/
if exists(select * from sysobjects where id = object_id('Survey'))
   drop table Survey
go

create table Survey
(
  ID        int         identity Primary key    not null ,
  SurveyID    varchar(20)    default ""         not null ,
  Kind        tinyint        default 0        not null ,
  Title        nvarchar(100)    default ""        not null ,
  Description    nvarchar(255)    default ""        not null ,
  Amount    int        default 0         not null ,
  BeginTime    datetime    default getdate()    not null ,
  EndTime    datetime    default getdate()    not null ,
  Active    bit        default 0        not null
)        
go

好了，数据库建好了，我可以从上面的survey基类中继承出具体的子类，比如说我现在要做一个同足球相

关的调查，那就做这么一个类：

namespace Football
{
    using System;
    using MyClass.Util ;
    using System.Data.SQL ;
    using System.Collections ;
    /// <summary>
    ///    足球舆论调查
    /// </summary>
    /// <remarks>
    /// 从MyClass.Util.Survey类继承而来
    /// </remarks>
    public class FootballSurvey : MyClass.Util.Survey
    {


        public FootballSurvey()
        {
        }


        /// <summary>
        /// 重载父类虚函数
        /// </summary>
        /// <param name="a_intID">该调查的数据库id </param>
        public override void LoadFromDatabase(string a_strID)
        {
            MyClass.Util.MyConnection myConn = new MyConnection() ;
            SQLCommand myCommand = new SQLCommand() ;
            myCommand.CommandText = "up_GetSurvey" ;
            myCommand.CommandType = System.Data.CommandType.StoredProcedure ;

            try
            {
                myConn.Open() ;
                myCommand.ActiveConnection = myConn ;
                myCommand.Parameters.Add(new SQLParameter("a_strsurveyid" ,

SQLDataType.VarChar , 20)) ;
                myCommand.Parameters["a_strsurveyid"].Value = a_strID ;
                SQLDataReader myReader ;
                myCommand.Execute(out myReader) ;

                //先取调查
                if (myReader.Read())
                {
                    this.m_strTitle = myReader["title"].ToString() ;
                    this.m_intHits = (int)myReader["amount"] ;
                    this.m_strID = a_strID ;
                    this.m_datBeginTime =

(DateTime)myReader["begintime"] ;
                    this.m_datEndTime = (DateTime)myReader["endtime"] ;
                }
                else
                {
                    throw(new Exception("数据库中无此调查的纪录")) ;
                }

                //清空调查项
                m_arrItems.Clear() ;

                //取调查项
                if (myReader.HasMoreRows)
                {
                    while(myReader.Read())
                    {
                        SurveyItem item = new SurveyItem() ;
                        item.Text = myReader["title"].ToString() ;
                        item.ID = (int)myReader["id"] ;
                        item.Count = (int)myReader["amount"] ;
                        item.Description =

myReader["Description"].ToString() ;
                        AddItem(item) ;
                    }
                }
                else
                {
                    throw(new Exception("数据库中没有该调查相关的调查项

")) ;
                }

                //清场
                myReader.Close() ;
                myConn.Close() ;
            }
            catch(Exception e)
            {
                throw(new Exception("从数据库中读取调查失败：" +

e.ToString())) ;
            }
        }


        /// <summary>
        /// 将调查保存到数据库
        /// </summary>
        /// <param name="m_strSurveyID">调查编号 </param>
        /// <remarks>
        /// 如果m_strSurveyID不为空，则删除原纪录，用当前调查编号保存新的调查，
        /// 否则就生成一个新的调查编号
        /// </remarks>
        public override void SaveToDatabase(string m_strSurveyID)
        {
            //如果没有标题或调查项则抛出异常
            if (this.m_arrItems.Count == 0 || this.m_strTitle == "")
            {
                throw(new Exception("没有调查标题或标题项")) ;
            }

            MyClass.Util.MyConnection myConn = new MyConnection() ;
            SQLCommand myCommand = new SQLCommand() ;
            myCommand.CommandType = System.Data.CommandType.Text ;
            
            try
            {
                myConn.Open() ;
                myCommand.ActiveConnection = myConn ;

                //如果没有surveyid则生成surveyid
                string strSurveyID ;
                if(m_strSurveyID == "")
                {
                    strSurveyID = DateTime.Now.Year.ToString()
                                +

DateTime.Now.Month.ToString()
                                +

DateTime.Now.Hour.ToString()
                                +

DateTime.Now.Minute.ToString()
                                +

DateTime.Now.Second.ToString()
                                +

DateTime.Now.Millisecond.ToString() ;
                }
                else    //如果已有，则删除该条纪录
                {
                    strSurveyID = m_strSurveyID ;
                    //删除原有纪录
                    myCommand.CommandText = "delete from survey where

surveyid='" + strSurveyID + "'" ;
                    myCommand.ExecuteNonQuery() ;
                }

                string strSql = "insert into survey(surveyid , kind , title)

values ('"
                                + strSurveyID +"', 0 , '" +

m_strTitle + "')\r\n" ;
                for (int i = 0 ; i < m_arrItems.Count ; i ++)
                {
                    strSql += "insert into survey(surveyid , kind ,

title) values('"
                        + strSurveyID + "' , 1 , '"
                        + ((SurveyItem)m_arrItems[i]).Text +

"')\r\n" ;
                }
                //插库
                myCommand.CommandText = strSql ;
                myCommand.ExecuteNonQuery() ;

                //清场
                myConn.Close() ;
            }
            catch(Exception e)
            {
                throw(new Exception("保存调查时出错：" +  e.ToString())) ;
            }
            
        }

        /// <summary>
        /// 投票
        /// </summary>
        /// <param name="a_intID"> </param>
        public override void Vote(int a_intID)
        {
            //该项计数加一
            ((SurveyItem)m_arrItems[a_intID]).Count += 1 ;

            //数据库中改变
            MyConnection myConn = new MyConnection() ;
            SQLCommand myCommand = new SQLCommand() ;
            myCommand.CommandText = "update survey set amount=amount+1 where

id="
                                    +

((SurveyItem)m_arrItems[a_intID]).ID.ToString() ;

            myCommand.CommandType = System.Data.CommandType.Text ;

            try
            {
                myConn.Open() ;
                myCommand.ActiveConnection = myConn ;
                myCommand.ExecuteNonQuery() ;
                myConn.Close() ;
            }
            catch(Exception e)
            {
                throw(new Exception("更新调查项失败:" + e.ToString())) ;
            }
        
        }

        /// <summary>
        /// 调查列表
        /// </summary>
        public static ArrayList SurveyList()
        {
            ArrayList arrResult = new ArrayList() ;
            MyClass.Util.MyConnection myConn = new MyConnection() ;
            SQLCommand myCommand = new SQLCommand() ;
            myCommand.CommandText = "select id , surveyid , title from survey

where kind=0 order by surveyid desc" ;
            myCommand.CommandType = System.Data.CommandType.Text ;

            try
            {
                myConn.Open() ;
                myCommand.ActiveConnection = myConn ;
                SQLDataReader myReader ;
                myCommand.Execute(out myReader) ;
                while (myReader.Read())
                {
                    FootballSurvey mySurvey = new FootballSurvey() ;
                    mySurvey.Title = myReader["title"].ToString() ;
                    mySurvey.SurveyID = myReader["surveyid"].ToString()

;
                    arrResult.Add(mySurvey) ;
                }

                myReader.Close() ;
                myConn.Close() ;

            }
            catch(Exception e)
            {
                throw(new Exception("从数据库中取出调查失败:" +

e.ToString())) ;
            }

            //返回结果
            return arrResult ;
        }

        /// <summary>
        /// 取得激活的调查id
        /// </summary>
        public static string GetActiveSurveyID()
        {
            string strResult = "" ;

            MyClass.Util.MyConnection myConn = new MyConnection() ;
            SQLCommand myCommand = new SQLCommand() ;
            myCommand.CommandText = "select top 1 id , surveyid from survey

where active=1 order by id desc" ;
            myCommand.CommandType = System.Data.CommandType.Text ;

            try
            {
                myConn.Open() ;
                myCommand.ActiveConnection = myConn ;
                SQLDataReader myReader ;
                myCommand.Execute(out myReader) ;
                if (myReader.Read())
                {
                    strResult = myReader["surveyid"].ToString() ;
                }
                else
                {
                    throw(new Exception("没有激活的调查")) ;
                }

                myReader.Close() ;

            }
            catch(Exception e)
            {
                throw(new Exception("从数据库中取出调查失败:" +

e.ToString())) ;
            }
            finally
            {
                myConn.Close() ;
            }

            //返回结果
            return strResult ;

        }

        /// <summary>
        /// 激活调查
        /// </summary>
        /// <param name="a_strSurveyID">调查编号 </param>
        public static void ActiveSurvey(string a_strSurveyID)
        {
            MyClass.Util.MyConnection myConn = new MyClass.Util.MyConnection() ;
            SQLCommand myCommand = new SQLCommand() ;
            myCommand.CommandText = "update survey set active=0 ;"
                                    + "update survey set

active=1 where surveyid='" + a_strSurveyID + "'" ;
            myCommand.CommandType = System.Data.CommandType.Text ;

            try
            {
                myConn.Open() ;
                myCommand.ActiveConnection = myConn ;
                myCommand.ExecuteNonQuery() ;
            }
            catch(Exception exp)
            {
                throw(new Exception("保存激活调查到数据库出错：" +

exp.ToString()));
            }
            finally
            {
                myConn.Close() ;
            }
        }

    }
}