省级三联动不用三层架构的（sql源码）

sql2008

省
create table Province(ProvinceID int primary key,ProvinceName nvarchar(50),)
insert into Province values (1,'北京市')
insert into Province values (2,'天津市')
insert into Province values (3,'河北省')

市
create table City(CityID int primary key,CityName nvarchar(50),ProvinceID int)
insert into Province values (1,'北京市',1)
insert into Province values (2,'天津市',2)
insert into Province values (3,'石家庄',3)
insert into Province values (4,'唐山',3)
insert into Province values (5,'保定',3)
insert into Province values (6,'邯郸',3)
县
create table District(DistrictID int primary key,DistrictName nvarchar(50),CityID int )
insert into Province values (1,'东城区',1)
insert into Province values (2,'西城区',1)
insert into Province values (3,'和平区',2)
insert into Province values (4,'河东区',2)
insert into Province values (5,'路北区',4)
insert into Province values (6,'路南区',4)

 

后台：

namespace 各种格式的省级联动
{
    public partial class 普通的 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                loadProvince();
            }
        }
        private void loadProvince()
        {
            string contor = ConfigurationManager.ConnectionStrings["strcon"].ConnectionString;
            SqlConnection coon = new SqlConnection(contor);
            coon.Open();
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = coon;
            cmd.CommandText = "select * from S_Province";
            SqlDataAdapter apter = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            apter.Fill(dt);
            coon.Dispose();
            cmd.Dispose();
            DropDownList1.DataSource = dt;
            DropDownList1.DataTextField = "ProvinceName";
            DropDownList1.DataValueField = "ProvinceID";
            DropDownList1.DataBind();
        }
        protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (this.DropDownList2.Items.Count>0)
            {
                this.DropDownList2.Items.Clear();
            }
            string provid = this.DropDownList1.SelectedItem.Value;
            string contor = ConfigurationManager.ConnectionStrings["strcon"].ConnectionString;
            SqlConnection coon = new SqlConnection(contor);
            coon.Open();
            SqlCommand cmd=new SqlCommand ();
            cmd.Connection=coon;
            cmd.CommandText = "select * from S_City where ProvinceID='" + provid + "'";
            SqlDataAdapter adap = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            adap.Fill(dt);
            coon.Dispose();
            cmd.Dispose();
            DropDownList2.DataSource = dt;
            DropDownList2.DataTextField = "cityname";
            DropDownList2.DataValueField = "cityID";
            DropDownList2.DataBind();
        }

        protected void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)
        {
            string provid = this.DropDownList2.SelectedItem.Value;
            string contor = ConfigurationManager.ConnectionStrings["strcon"].ConnectionString;
            SqlConnection coon = new SqlConnection(contor);
            coon.Open();
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = coon;
            cmd.CommandText = "select * from S_District where CityID='" + provid + "'";
            SqlDataAdapter adta = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            adta.Fill(dt);
            coon.Dispose();
            cmd.Dispose();
            DropDownList3.DataSource = dt;
            DropDownList3.DataTextField = "DistrictName";
            DropDownList3.DataValueField = "DistrictID";
            DropDownList3.DataBind();
        }
    }
}

web配置： <add name="strcon" connectionString="Data Source=计算机名字;Initial Catalog=CityandContury;Persist Security Info=True;User ID=账号 ;Password=密码"/>

 

前台 ：

  DropDownList  的属性AutoPostBack="True”