Three Layer Architecture in C# .NET

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

namespace ThreeLayerDemo.Core
{
    /// <summary>
    /// Summary description for UserBUS
    /// </summary>
    public class UserBUS
    {
        private UserDAO _userDAO;

        /// <constructor>
        /// Constructor UserBUS
        /// </constructor>
        public UserBUS()
        {
            _userDAO  = new UserDAO();
        }

        /// <method>
        /// Get User Email By Firstname or Lastname and return VO
        /// </method>
        public UserVO getUserEmailByName(string name)
        {
            UserVO userVO = new UserVO();
            DataTable dataTable = new DataTable();

            dataTable = _userDAO.searchByName(name);

            foreach (DataRow dr in dataTable.Rows)
            {
                userVO.idUser = Int32.Parse(dr["t01_id"].ToString());
                userVO.firstname = dr["t01_firstname"].ToString();
                userVO.lastname = dr["t01_lastname"].ToString();
                userVO.email = dr["t01_email"].ToString();
            }
            return userVO;
        }

        /// <method>
        /// Get User Email By Id and return DalaTable
        /// </method>
        public UserVO getUserById(string _id)
        {
            UserVO userVO = new UserVO();
            DataTable dataTable = new DataTable();
            dataTable = _userDAO.searchById(_id);

            foreach (DataRow dr in dataTable.Rows)
            {
                userVO.idUser = Int32.Parse(dr["t01_id"].ToString());
                userVO.firstname = dr["t01_firstname"].ToString();
                userVO.lastname = dr["t01_lastname"].ToString();
                userVO.email = dr["t01_email"].ToString();
            }
            return userVO;
        }
    }
}