大家帮忙看看哪有有问题了 谢谢

Question

 private void Bind()
    {
        DataTable dt = TruckRules.TruckChinaProvinceRules.SelectChinaProvinceList();        if (dt != null)
        {
            foreach (DataRow dr in dt.Rows)
            {
                this.DropDownList1.Items.Add(new ListItem(dr["F_ProvinceName"].ToString(), dr["F_ProvinceId"].ToString()));
            }
        }
    }
    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        string F_ProvinceId = this.DropDownList1.SelectedValue;        DataTable dt = TruckRules.TruckChinaProvinceRules.SelectProvinceByCityPidFill(F_ProvinceId);        if (dt != null)
        {
            foreach (DataRow dr in dt.Rows)
            {
                this.DropDownList2.Items.Add(new ListItem(dr["F_CityName"].ToString(), F_ProvinceId));
            }
        }
    }
    protected void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)
    {
        string F_CityId = this.DropDownList2.SelectedValue;        DataTable dt = TruckRules.TruckChinaProvinceRules.GetCityByAreasFill(F_CityId);        if (dt != null)
        {
            foreach (DataRow dr in dt.Rows)
            {
                this.DropDownList3.Items.Add(new ListItem(dr["F_AreaName"].ToString(), F_CityId));
            }
        }
    }这个是控件的级联   第一个方法是显示所有的  然后点击第一个下拉框   怎么没有反应 大家帮忙看看哪有有问题了 谢谢

Answer 1

DropDownList1的AutoPostBack要设置为True,不然不会回发

Answer 2

你是否启用了AutoPostBack 
this.DropDownList1.AutoPostBack = true;还是用js+ajax局部刷新吧