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();

    }