um.UserName = this.TextBox1.Text;
            um.UserPwd = this.TextBox2.Text;
            um.DepartMentName = this.DropDownList1.SelectedItem.Text;
            if(ub.Login(um))
            {
                Response.Redirect("Admin.aspx");
            }

 public bool Login(UserModel um)
        {
            return userdal.Login(um);
        }

  public bool Login(UserModel um)
         {
             bool flag = false;
             string sql = "select * from Users where UserName=@username and UserPwd=@userpwd and DepartMentName=@departmentname";
             SqlParameter[] paras = new SqlParameter[]{
              new SqlParameter("username",um.UserName),
              new SqlParameter("userpwd",um.UserPwd),
              new SqlParameter("departmentname",um.DepartMentName)
             };
             int res = sqlhelper.CheckLogin(sql, paras, CommandType.Text);
             if (res > 0)
             {
                 flag = true;
             }
             return flag;
         }

 public int CheckLogin(string CmdText, SqlParameter[] paras, CommandType ct)
        {
            int res;
            using (cmd = new SqlCommand(CmdText, Getconn()))
            {
                cmd.CommandType = ct;
                cmd.Parameters.AddRange(paras);
                res = cmd.ExecuteNonQuery();
            }
            return res;
        }

 SqlConnection conn = new SqlConnection("server=.;uid=customer adm;pwd=6568986z;database=customer");
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = conn;
            cmd.CommandText = "select*from cdetials where uname='"+this.textBox1.Text+"'";---执行tsql语句，读取数据库中的信息
            conn.Open();
            SqlDataReader dr = cmd.ExecuteReader();---  SqlDataReader读取行的操作，ExecuteReader()执行读取
            if (dr.HasRows)————读取第一个值，即第一个uname
            {
                dr.Read();————继续读下一条
                if (this.textBox2.Text == dr["upwd"].ToString())
                {
                    Form2 f2 = new Form2();
                    f2.Show();
                    this.Visible = false;
                }
                    
                else
                    MessageBox.Show("密码错误!");
            }
            else
                MessageBox.Show("账号错误!");
            conn.Close();