dropdownlist 联动选择

背景：visual studio 2005 ;

             实现选择省时，自动显示所属的城市列表

实现：省:dropdownlist---.ddlProvince ----AutoPostBack="True";

             市:dropdowncity---ddlCity; /listbox---lbCity

代码：

数据库设计：

 

create database db_pro_city
go
use db_pro_city
go
create table tb_pro
(
   proID int primary key,
   proName varchar(50) not null
)
go
insert into tb_pro values(1,'北京')
insert into tb_pro values(2,'江苏')
insert into tb_pro values(3,'安徽')
insert into tb_pro values(4,'湖北')
go
select * from tb_pro
go
create table tb_city
(
  cityID int primary key,
  proID int foreign key references  tb_pro(proID),
  cityName varchar(50) not null
)
go
insert into tb_city values(1,1,'北京')
insert into tb_city values(2,2,'南京')
insert into tb_city values(3,2,'苏州')
insert into tb_city values(4,2,'盐城')
insert into tb_city values(5,3,'芜湖')
insert into tb_city values(6,3,'合肥')
insert into tb_city values(7,4,'黄冈')
insert into tb_city values(8,4,'湖北')
go

 

数据库连接DB.cs:

public  static SqlConnection createCon()
    {
        return new SqlConnection("server=localhost\\sqlexpress;database=db_pro_city;uid=sa;pwd=hello");
    }

加载页面代码：

 protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            //绑定省
            SqlConnection con = DB.createCon();
            con.Open();
            SqlCommand cmdpro = new SqlCommand("select * from tb_pro", con);
            SqlDataReader sdrpro = cmdpro.ExecuteReader();
            this.ddlProvince.DataSource = sdrpro;
            this.ddlProvince.DataTextField = "proName";
            this.ddlProvince.DataValueField = "proID";
            this.ddlProvince.DataBind();
            sdrpro.Close();
            //绑定市
            SqlCommand cmdcity = new SqlCommand("select * from tb_city where proID=" + this.ddlProvince.SelectedValue, con);
            SqlDataReader sdrcity = cmdcity.ExecuteReader();
            this.ddlCity.DataSource = sdrcity;
            this.ddlCity.DataTextField = "cityName";
            this.ddlCity.DataValueField = "cityID";
            this.ddlCity.DataBind();
            sdrcity.Close();
            con.Close();
        }
    }
    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        SqlConnection con = DB.createCon();
        con.Open();
        SqlCommand cmdcity=new SqlCommand("select * from tb_city where proID=" + this.ddlProvince.SelectedValue, con);
        SqlDataReader sdrcity = cmdcity.ExecuteReader();
        this.ddlCity.DataSource = sdrcity;
        this.ddlCity.DataTextField = "cityName";
        this.ddlCity.DataValueField = "cityID";
        this.ddlCity.DataBind();
        sdrcity.Close();
        con.Close();

    }

 

 

//listbox代码.循环取值，并将值添加到ListBox

 

            SqlCommand cmdcity = new SqlCommand("select * from tb_city where proID=" + this.ddlProvince.SelectedValue, con);
            SqlDataReader sdrcity = cmdcity.ExecuteReader();

           while(sdrcity.Read())

{

            //ListBox之text字段为：cityName第3列， value字段为：cityID第1列；

            this.lbCity.Items.Add(new ListBox(sdrcity.GetStrint(2),sdrcity.GetInt32(0).ToString())

}