省市县三级联动（第三种的方法）

namespace 省市县三级联动{    public partial class WebPCA : System.Web.UI.Page    {        protected void Page_Load(object sender, EventArgs e)        {            if(!IsPostBack)            {                Province();            }        }

        private DataTable LoadData(string id)        {            string constr = ConfigurationManager.ConnectionStrings["ConStr"].ConnectionString;            SqlConnection conn = new SqlConnection(constr);            conn.Open();            SqlCommand cmd = new SqlCommand();            cmd.Connection = conn;            cmd.CommandText = "SELECT A_Id,A_Name FROM T_Arear WHERE A_ParentId=@pid ORDER BY A_Id";            cmd.Parameters.AddWithValue("@pid", id);            SqlDataAdapter adapter = new SqlDataAdapter(cmd);            DataTable dt = new DataTable();            adapter.Fill(dt);            cmd.Dispose();            conn.Dispose();            return dt;        }        private void Province()        {            DataTable dt = LoadData("0");            this.ddlProvince.DataSource = dt;            //提供文本内容数据源字段            this.ddlProvince.DataTextField = "A_Name";            //提供值的数据源的字段            this.ddlProvince.DataValueField = "A_Id";            //将数据源绑定到下拉列表当中            this.ddlProvince.DataBind();            ListItem item = new ListItem("-------请选择-------","0");            //设置为默认            this.ddlProvince.Items.Insert(0, item);        }

、、、、、、、、、、、城市选择部分、、、、、、、、、、、、、、、、、、、、

        protected void ddlProvince_SelectedIndexChanged(object sender, EventArgs e)        {            string id = this.ddlProvince.SelectedItem.Value;            if (id != "0")            {                DataTable dt = LoadData(id);

                this.ddlCity.DataSource = dt;                //指定下拉列表要显示的字段的值                this.ddlCity.DataTextField = "A_Name";                //指定下拉列表的value属性要绑定的字段的值                this.ddlCity.DataValueField = "A_Id";                this.ddlCity.DataBind();

                //绑定默认显示的市下面的区县                string selectid = this.ddlCity.SelectedItem.Value;                DataTable dt1 = LoadData(selectid);                this.ddlArea.DataSource = dt1;                //指定下拉列表要显示的字段的值                this.ddlArea.DataTextField = "A_Name";                //指定下拉列表的value属性要绑定的字段的值                this.ddlArea.DataValueField = "A_Id";                this.ddlArea.DataBind();            }            else            {                ddlCity.Items.Clear();                ddlArea.Items.Clear();            }            //Response.Write(id);        }

、、、、、、、、、、、、、县（区）选择部分、、、、、、、、、、、、、、、、、、、、、、、、、

        protected void ddlCity_SelectedIndexChanged(object sender, EventArgs e)        {           string idd= ddlCity.SelectedItem.Value;           DataTable dt = LoadData(idd);           this.ddlArea.DataSource = dt;           this.ddlArea.DataTextField = "A_Name";           this.ddlArea.DataValueField = "A_Id";           this.ddlArea.DataBind();        }    } }

程序运行结果如图所示：

转载于:https://www.cnblogs.com/qzc900809/archive/2013/03/14/2960202.html

相关资源：js实现省市地区三级联动并获取省市县的值