dropDownList与数据库SQL 2000的事例

SQL.TXT 文件

create database dropDownTest

use dropDownTest

create table province
(
 proID int primary key,
 proName varchar(50) not null
)

insert into province values (1,'北京')
insert into province values (2,'吉林')
insert into province values (3,'辽宁')
insert into province values (4,'黑龙江')
insert into province values (5,'山东')

create table city
(
 cityID int primary key,
 proID int foreign key references province(proID),
 cityName varchar(50) not null
)
insert into city values(1,1,'北京')
insert into city values(2,2,'长春')
insert into city values(3,2,'吉林')
insert into city values(4,3,'沈阳')
insert into city values(5,3,'大连')
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Default.aspx 页面

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!this.IsPostBack)
        {  
            //查询province表的内容--省的内容
            SqlConnection con = DB.createConnection();
            con.Open();
            SqlCommand cmd = new SqlCommand("select * from province",con);
            SqlDataReader sdr = cmd.ExecuteReader();
            this.ddlProvince.DataSource = sdr;
            this.ddlProvince.DataTextField = "proName";
            this.ddlProvince.DataValueField = "proID";
            this.ddlProvince.DataBind();
            sdr.Close();

            //查询city的内容--省对应市的内容－－绑定初始状态
            SqlCommand cmdCity = new SqlCommand("select * from city where proID="+this.ddlProvince.SelectedValue,con);
            SqlDataReader sdr1 = cmdCity.ExecuteReader();
            this.ddlCity.DataSource = sdr1;
            this.ddlCity.DataTextField = "cityName";
            this.ddlCity.DataValueField = "cityID";
            this.ddlCity.DataBind();
            sdr1.Close();
            //关闭数据连接
            con.Close();
        }
    }
    protected void btn_Click(object sender, EventArgs e)
    {
        this.ListBox1.Items.Add(this.txtbox.Text);
    }
    protected void ListBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        this.Label1.Text = "你选中了" + this.ListBox1.SelectedItem.Text;
    }
    protected void ddlProvince_SelectedIndexChanged(object sender, EventArgs e)
    {
        //查询city的内容--省对应市的内容－－动态绑定
        String proID = this.ddlProvince.SelectedValue;
        SqlConnection con = DB.createConnection();
        con.Open();
        SqlCommand cmd = new SqlCommand("select * from city where proID=" + this.ddlProvince.SelectedValue, con);
        SqlDataReader sdr = cmd.ExecuteReader();
        this.ddlCity.DataSource = sdr;
        this.ddlCity.DataTextField = "cityName";
        this.ddlCity.DataValueField = "cityID";
        this.ddlCity.DataBind();
        sdr.Close();
        //关闭连接
        con.Close();
    }
}