给你个例子[.NET中三层构架开发实例

数据库基类
using System;
using System.Data;
using System.Data.SqlClient;

namespace HaiSky.HtJob
{
    /// <summary>
    /// DbClass 的摘要说明。
    /// </summary>
    public class DbClass
    {
        private string connectionString;
        protected SqlConnection Connection;
        public DbClass(string newConnectionString)
        {
            connectionString = newConnectionString;
            Connection = new SqlConnection(connectionString);
        }
        public string ConnectionString
        {
            get
            {
                return connectionString;
            }
        }
        private SqlCommand BuildQueryCommand(string storedProcName,IDataParameter[] parameters)
        {
            SqlCommand command = new SqlCommand(storedProcName,Connection);
            command.CommandType = CommandType.StoredProcedure;
            foreach (SqlParameter parameter in parameters)
                {
                    command.Parameters.Add(parameter);
                }
            return command;
        }
        private SqlCommand BuildIntCommand(string storedProcName,IDataParameter[] parameters)
        {
            SqlCommand command = BuildQueryCommand(storedProcName,parameters);
            command.Parameters.Add(new SqlParameter("ReturnValue",SqlDbType.Int,4,
                ParameterDirection.ReturnValue,false,
                0,
                0,
                string.Empty,DataRowVersion.Default,null));
            return command;        
        }
        protected int RunProcedure(string storedProcName,IDataParameter[] parameters,out int rowsAffected)
        {
            int result;
            Connection.Open();
            SqlCommand command = BuildIntCommand(storedProcName,parameters);
            rowsAffected = command.ExecuteNonQuery();
            result = (int)command.Parameters["ReturnValue"].Value;
            Connection.Close();
            return result;
        }
        protected SqlDataReader RunProcedure(string storedProcName, IDataParameter[] parameters )
        {
            SqlDataReader returnReader;

            Connection.Open();
            SqlCommand command = BuildQueryCommand( storedProcName, parameters );
            command.CommandType = CommandType.StoredProcedure;

            returnReader = command.ExecuteReader();
            return returnReader;
        }
        protected DataSet RunProcedure(string storedProcName, IDataParameter[] parameters, string tableName )
        {
            DataSet dataSet = new DataSet();
            Connection.Open();
            SqlDataAdapter sqlDA = new SqlDataAdapter();
            sqlDA.SelectCommand = BuildQueryCommand( storedProcName, parameters );
            sqlDA.Fill( dataSet, tableName );
            Connection.Close();

            return dataSet;
        }
        protected void RunProcedure(string storedProcName, IDataParameter[] parameters, DataSet dataSet, string tableName )
        {
            Connection.Open();
            SqlDataAdapter sqlDA = new SqlDataAdapter();
            sqlDA.SelectCommand = BuildIntCommand( storedProcName, parameters );
            sqlDA.Fill( dataSet, tableName );
            Connection.Close();            
        }
    }
}

商务层基类（逻辑层）
using System;
namespace Wrox.WebModules.Business
{
    public class BizObject
    {
        public BizObject()
        {            }
    }
}

下面是用户注册系统开发的三层构架实例：数据库基类采用上面提供的代码。
1、    用户注册模块数据层开发：
using System;
using System.Data;
using System.Data.SqlClient;
using HaiSky.HtJob;
using System.Xml;
namespace HaiSky.HtJob.Accounts.AccountsData
{
    public class User : HaiSky.HtJob.HaiSkyDbObject
    {
        public User(string newConnectionString) : base(newConnectionString)
        {//直接路由连接字符串}
        public int Create(string user_nm,string user_pwd)
        {
            int rowsAffected;
            SqlParameter[] parameters = {new SqlParameter("@user_nm",SqlDbType.Char,16),
                                        new
SqlParameter("@user_pwd",SqlDbType.Char,16)};
            parameters[0].Value = user_nm;
            parameters[1].Value = user_pwd;
            parameters[2].Direction = ParameterDirection.Output;
            try
            {
                RunProcedure("IF_user_info",parameters,out rowsAffected);
            }
            catch
            {    }
            return (int)parameters[2].Value;
        }
    }
}
2、用户注册商务层开发：
using System;
using System.Configuration;
using HaiSky.HtJob.Accounts.AccountsData;
namespace HaiSky.HtJob.Accounts.AccountBusiness
{
    public class User : HaiSky.HtJob.HaiSkyBizObject
    {
        int userID;
        string userName;
        string userPwd;
        string strConn;
        public User()
        {
            strConn = ConfigurationSettings.AppSettings["strConn"];
        }
        public int Careate()
        {
            AccountsData.User dataUser = new AccountsData.User(strConn);
            userID = dataUser.Create(userName,userPwd);
            return userID;
        }
        public int UserID
        {
            get
            {
                return userID;
            }
            set
            {
                userID = value;
            }
        }
        public string UserName
        {
            get
            {
                return userName;
            }
            set
            {
                userName = value;
            }
        }
        public string UserPwd
        {
            get
            {
                return userPwd;
            }
            set
            {
                userPwd = value;
            }
        }
    }
}
3、    用户注册表示层开发：
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using HaiSky.HtJob.Accounts.AccountBusiness;

namespace HaiSky.HtJob.Modules.Accounts
{
    public class Register : System.Web.UI.Page
    {
        protected System.Web.UI.WebControls.TextBox TextBox1;
        protected System.Web.UI.WebControls.TextBox TextBox2;
        protected System.Web.UI.WebControls.Table Table1;
        protected System.Web.UI.WebControls.Button Button1;

        private void Page_Load(object sender, System.EventArgs e)
        {
            Table1.Rows[0].Cells[0].Visible = false;
        }
        #region Web Form Designer generated code
        override protected void OnInit(EventArgs e)
        {
            InitializeComponent();
            base.OnInit(e);
        }    
        private void InitializeComponent()
        {    
            this.Button1.Click += new System.EventHandler(this.Button1_Click);
            this.Load += new System.EventHandler(this.Page_Load);
        }
        #endregion
        private void Button1_Click(object sender, System.EventArgs e)
        {
            int i;
            HtJob.Accounts.AccountBusiness.User BusinessUser = new HtJob.Accounts.AccountBusiness.User();
            BusinessUser.UserName = TextBox1.Text;
            BusinessUser.UserPwd = TextBox2.Text;
            i = BusinessUser.Careate();
            Response.Write (i.ToString());                         //这里输出返回值
        }
    }
}
4、    该系统调用的存储过程：
CREATE PROCEDURE IF_user_info
(@user_nm char(16),@user_pwd char(16),@user_ID int output)
AS
    insert user_info(user_nm,user_pwd) values(@user_nm,@user_pwd)
set @user_ID = @@identity
    IF @@ERROR > 0
        BEGIN
        RAISERROR ('Insert of Article failed', 16, 1)
        RETURN 99
    END
GO