实验

[@more@]

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 (!Page.IsPostBack) {
//创建连接
SqlConnection con = DB.createConnection();//用自定义的DB类来完成
con.Open();

//绑定省
SqlCommand cmd = new SqlCommand("select * from province",con);
SqlDataReader sdr = cmd.ExecuteReader();
this.ddlProvince.DataSource = sdr;//指定数据源
this.ddlProvince.DataTextField = "proName";//指定列表的text
this.ddlProvince.DataValueField = "proID";//指定列表的value
this.ddlProvince.DataBind();//绑定数据
sdr.Close();//关闭数据集

//绑定市
SqlCommand cmd2 = new SqlCommand("select * from city where proID="+this.ddlProvince.SelectedValue, con);
SqlDataReader sdr2 = cmd2.ExecuteReader();
this.ddlCity.DataSource = sdr2;
this.ddlCity.DataTextField = "cityName";
this.ddlCity.DataValueField = "cityID";
this.ddlCity.DataBind();
sdr2.Close();

//关闭连接
con.Close(); 　　
}
}
protected void ddlProvince_SelectedIndexChanged(object sender, EventArgs e)//省列表的selectchanged事件处理
{
//创建连接
SqlConnection con = DB.createConnection();
con.Open();

//列出对应市
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();
con.Close();
}
}

//DB.cs

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;

///

/// DB 的摘要说明
///

public class DB
{
public DB()
{
//
// TODO: 在此处添加构造函数逻辑
//
}

public static SqlConnection createConnection(){//静态方法,类名直接调用
SqlConnection con=new SqlConnection("server=.;database=dropdownTest;uid=sa;pwd=123456");
return con;
}
}

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