asp.net 实现省市级联<简单方法1>

准备工作：数据库自带

1.前台代码部分:

  <asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
        <ContentTemplate>
          <asp:DropDownList ID="DropDownList1" runat="server" 
            onselectedindexchanged="DropDownList1_SelectedIndexChanged" 
            ontextchanged="DropDownList1_TextChanged" AutoPostBack=true>
        </asp:DropDownList>
        <br />
        <asp:DropDownList ID="ddl_city" runat="server" 
            onselectedindexchanged="ddl_city_SelectedIndexChanged">
        </asp:DropDownList>
      </ContentTemplate>
        </asp:UpdatePanel>

2.后台代码部分:

 protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            string sqlstr = "select * from promary";
            DataTable dt = sqlhelper.ExcuteDataTable(sqlstr);
            //1.显示什么数据
            DropDownList1.DataTextField = "proName";
            DropDownList1.DataValueField = "proId";
            DropDownList1.DataSource = dt;
            DropDownList1.DataBind();
        }
       
        
    }
  
    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        string proId = DropDownList1.SelectedValue.ToString();
        string sqlstr = string.Format("select * from city where proID={0}", proId);
        DataTable dt = sqlhelper.ExcuteDataTable(sqlstr);
        ddl_city.DataTextField = "cityName";
        ddl_city.DataValueField = "cityId";
        ddl_city.DataSource = dt;
        ddl_city.DataBind();
    }