protected void Button1_Click(object sender, EventArgs e)
    {
        
        if (this.name.Text != "")//判断用户名是否未空
        {
         if (this.pwd.Text != "")//判断密码是否未空
         {
               if (this.yanzhen1.Text != "")//判断验证码是否未空
           {
            if (this.yanzhen1.Text == this.Label1.Text)//判断验证码是否相等
               {

                   try
                   {
                       OleDbConnection m_conn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" + Server.MapPath("./app_data/library.mdb"));
                       m_conn.Open();

                       OleDbCommand cmd = new OleDbCommand("select * from Administrator where 用户名=" + this.name.Text + "and 密码=" + this.pwd.Text, m_conn);    //建立sql查询语句

  int state = Convert.ToInt32(cmd.ExecuteScalar());           
                           if (state == 0 || state > 1)                              
                           {
                               this.Label2.Text = "用户不存在，请检测用户名和密码是否正确！";
                           }
                                  else
                                 {            this.Label2.Text = "登入成功！";              }
                          
                                
             m_conn.Close();}
              
                           catch (Exception a)
                               {    Response.Redirect("Default2.aspx");        }   
                           }
                  

            
                  else
                   {          this.Label2.Text = "验证码不正确，请重新输入！";         }   
                  }
            
             else
              {    this.Label2.Text = "验证码没有填写！";           }     
               }

        else
         {         this.Label2.Text = "密码没有填写！";                 }  
        }

程序是运行成功的，问题是只要验证码一样，用户名和密码和ACCESS表内的有无相同的数据，也可以到另一个网页，我是新手，请高人们看看是什么问题

先谢谢大家帮忙，异常是已经解决了，但无法判断用户和密码是否和ACCESS表内的一致，用户是否存在

也试过了，但都是无法判断用户和密码是否和ACCESS表内的一致，用户是否存在。
 if (state != 1)
            {
                this.Label2.Text = "用户不存在，请检测用户名和密码是否正确！";
            }
            else
            {
                this.Label2.Text = "登入成功！";
            }
        }
这个判断语句无执行

label2什么都无显示出来

异常就是label2无显示是否成功登录，试过换成转到另一个页面也不行， 库的连接我测过，可以的，用SQL也行