调试易

大家帮我看看到底是哪里错了？数据库名字：购物系统    表：用户表    字段：序列编号、姓名、密码。protected void Login_Click(object sender, EventArgs e)
        {
            string username = tbUsername.Text;
            string password = tbPassword.Text;
           
           string ConnectionString = "Server=(local);User id=sa;Pwd=123;Database=购物系统";//连接数据库字符串 
            string Sql = "SELECT   *   FROM   用户表   WHERE   姓名='" + username+ "'";
            
            SqlConnection Connection = new SqlConnection(ConnectionString);   //创建SqlConnection对象 
            SqlCommand Command = new SqlCommand(Sql, Connection);            Command.CommandText = "SELECT   密码    FROM   用户表   where   姓名='" + username + "'";
 
             Command.CommandType = CommandType.Text;            try
            {
                Command.Connection.Open();//打开数据库连接                  
                object test = Command.ExecuteScalar();//获取查询结果  
                Response.Write (test);      
                SqlDataReader dr = Command.ExecuteReader();//执行SQL语句返回DataReader对象
                while (dr.Read())
                {
                    string strpassword = dr["密码"].ToString();//强制转换成STRING型数据   
                    Response.Write(strpassword);                    if (password == strpassword)
                    {
                        Response.Redirect("default.aspx");
                    }
                    else
                    {
                        string message = ("对不起,您输入的内容有误!");
                        Response.Redirect("index.aspx?MSG=" + message);
                    }                }
               
                dr.Close();  //关闭   DataReader               }
            catch (SqlException ex)
            {
                //Response.Write   ("数据库连接失败");   
                //Response.Write   (ex);   
            }
            finally
            {
                Connection.Close();//关闭数据库
                Command.Connection.Close();  //关闭数据库连接               }           }