VISUAL2013找不到类怎么办,已经添加进去了还是找不到SQLHELP类

Question

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using DAL;
using System.Data.SqlClient;

namespace 图书借阅管理系统
{
    public partial class 登陆 : Form
    {
        public 登陆()
        {
            InitializeComponent();
        }

        private void label4_Click(object sender, EventArgs e)
        {
        }

        private void 登陆_Load(object sender, EventArgs e)
        {
            Random r = new Random();
            label4.Text = r.Next(1000, 9999).ToString();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            int role;
            if(textBox3.Text==label4.Text)
            {
                if (radioButton1.Checked) role = 0;
                else role = 1;
                SqlParameter[] p ={
                                      new SqlParameter("@UserName",textBox1.Text),
                                      new SqlParameter("@PassWord",textBox2.Text),
                                      new SqlParameter("@Role",role)
                                  };
                SqlDataReader dr=SQLHELPER.（到这就提示不存在sqlhelp）
            }
        }
    }
}

Answer 1

注意sqlhelper里的namespace是不是namespace 图书借阅管理系统
如果不是，加上对应的using