三级联动方法二

 string sqlcon = ConfigurationManager.ConnectionStrings["sqlservercon"].ConnectionString;        protected void Page_Load(object sender, EventArgs e)        {            if(!IsPostBack)            {                GetProvince();            }        }        public void GetProvince()         {             SqlConnection conn = new SqlConnection(sqlcon);            conn.Open();            SqlCommand cmd=new SqlCommand();            cmd.Connection=conn;            cmd.CommandText = "select provincename,provinceID from province";            SqlDataAdapter adapter = new SqlDataAdapter(cmd);            DataTable dt = new DataTable();            adapter.Fill(dt);            cmd.Dispose();            conn.Dispose();            this.ddlProvince.DataSource=dt;            this.ddlProvince.DataTextField = "provincename";            this.ddlProvince.DataValueField = "provinceID";            this.ddlProvince.DataBind();        }

        protected void ddlProvince_SelectedIndexChanged(object sender, EventArgs e)        {            每次加载的时候清空一下            ddlCity.Items.Clear();            int pid = Convert.ToInt32(ddlProvince.SelectedValue);

            SqlConnection conn = new SqlConnection(sqlcon);            conn.Open();            SqlCommand cmd = new SqlCommand();            cmd.Connection = conn;            cmd.CommandText = "select cityname,cityID from city where father=@father";            cmd.Parameters.AddWithValue("@father",pid);            //DataSet dt = new DataSet();            DataTable dt = new DataTable();            SqlDataAdapter adapter = new SqlDataAdapter(cmd);            adapter.Fill(dt);            cmd.Dispose();            conn.Dispose();            this.ddlCity.DataSource = dt;            this.ddlCity.DataTextField = "cityname";            this.ddlCity.DataValueField = "cityID";            this.ddlCity.DataBind();        }

        protected void ddlCity_SelectedIndexChanged(object sender, EventArgs e)        {            ddlArea.Items.Clear();            int cid = Convert.ToInt32(ddlCity.SelectedValue);            SqlConnection conn = new SqlConnection(sqlcon);            conn.Open();            SqlCommand cmd = new SqlCommand();            cmd.Connection = conn;            cmd.CommandText = "select areaname,areaID from area where father=@father";            cmd.Parameters.AddWithValue("@father", cid);            DataTable dt = new DataTable();            SqlDataAdapter adapter = new SqlDataAdapter(cmd);            adapter.Fill(dt);            cmd.Dispose();            conn.Dispose();            this.ddlArea.DataSource = dt;            this.ddlArea.DataTextField = "areaname";            this.ddlArea.DataValueField = "areaID";            this.ddlArea.DataBind();        }

转载于:https://www.cnblogs.com/qzc900809/archive/2013/05/31/3109505.html

相关资源：java三级联动