我把简单问题复杂化了：）[旧代码]

using  System;
using  System.Collections.Generic;
using  System.Text;

using  System.Data;
using  System.Data.OleDb;
using  System.Configuration;
using  System.Collections;

namespace  PatternsStudy1
{
     class  Program
    {
         ///   <summary>
         ///  程序入口点
         ///   </summary>
         ///   <param name="args"></param>
         static   void  Main( string [] args)
        {
            BorrowReader br  =   new  BorrowReader(GetNames);

             string  strSql  =   " SELECT * FROM ROCKET " ;

             foreach  ( string  str  in  LendReader(strSql, br))
            {
                Console.WriteLine(str);
            }
            
            Console.Read();
        }

         ///   <summary>
         ///  取得数据库连接实例
         ///   </summary>
         ///   <returns> 数据库连接实例 </returns>
         private   static  OleDbConnection CreateConnection()
        {
             // 读取应用程序配置节
             string  strDbConn  =   new  AppSettingsReader().GetValue( " dbconn " ,  typeof ( string )).ToString();
             // string strDbConn = ConfigurationManager.AppSettings["dbconn"];
             // Console.WriteLine(strDbConn);
             // 创建数据库连接对象
            OleDbConnection conn  =   new  OleDbConnection();
             // 设定数据库连接字符串
            conn.ConnectionString  =  strDbConn;
             // 返回数据库连接实例
             return  conn;
        }

         ///   <summary>
         ///  执行读取操作
         ///   </summary>
         ///   <param name="strSql"> 要执行的Sql语句 </param>
         ///   <param name="br"> 委托对象 </param>
         ///   <returns> 读取的结果 </returns>
         private   static  IEnumerable LendReader( string  strSql, BorrowReader br)
        {
            List < string >  list  =   new  List < string > ();
             using  (OleDbConnection conn  =  CreateConnection())
            {
                 // 打开数据库连接
                conn.Open();
                OleDbCommand olcom  =   new  OleDbCommand(strSql, conn);
                 // 执行读取
                OleDbDataReader oldr  =  olcom.ExecuteReader();
                list  =  br(oldr);
                 foreach  ( string  str  in  list)
                {
                    yield  return  str;
                }
            }
        }

         ///   <summary>
         ///  读取结果集
         ///   </summary>
         ///   <param name="idr"> 读取数据对象 </param>
         ///   <returns> 读取的数据集 </returns>
         private   static  List < string >  GetNames(IDataReader idr)
        {
            List < string >  list  =   new  List < string > ();
             while  (idr.Read())
            {
                list.Add(idr[ 1 ].ToString());
            }
             return  list;
        }
    }

     ///   <summary>
     ///  声明委托，用于取得数据
     ///   </summary>
     ///   <param name="idr"> 读取数据对象 </param>
     ///   <returns> 读取的数据集 </returns>
     public   delegate  List < string >  BorrowReader(IDataReader idr);
}

呵呵，复杂化了吧。