级联效果的下拉选择框 - 黑马程序员技术交流社区

//读取XML文档
XDocument XDoc2 = XDocument.Load(@"d:\caoyi.xml");
//获取根节点
XElement Root = XDoc2.Root;
//输出根节点的Name,Value
Console.WriteLine("Root.Name：{0}",Root.Name);//输出:Student
Console.WriteLine("Root.Value:{0}",Root.Value);//输出：dede22男
Console.WriteLine("Root.ToString：{0}",Root.ToString());//输出：节点下的整个XML
//获取子元素
XElement xEle1 =Root.Element("Name");//获取子元素组
Console.WriteLine(xEle1.Value);//输出：dede
foreach (XElement ele in Root.Elements())
{
Console.WriteLine("{0}-{1}",ele.Name,ele.Value);
}

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using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
using System.Configuration;
namespace 省市选择器
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
string dataDir = AppDomain.CurrentDomain.BaseDirectory;
if (dataDir.EndsWith(@"\bin\Debug\")
|| dataDir.EndsWith(@"\bin\Release\"))
{
dataDir = System.IO.Directory.GetParent(dataDir).Parent.Parent.FullName;
AppDomain.CurrentDomain.SetData("DataDirectory", dataDir);
}
string cnonStr = ConfigurationManager.ConnectionStrings["connStr"].ConnectionString; // 配置文件
using (SqlConnection conn = new SqlConnection(cnonStr))
{
conn.Open();
using (SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = "select * from promary";
using (SqlDataReader reader = cmd.ExecuteReader())
{
while (reader.Read())
{
provinceItem item = new provinceItem(); //产生一个Item对象
item.Id = reader.GetInt32(reader.GetOrdinal("proID")); //得到省的Id
item.Name = reader.GetString(reader.GetOrdinal("proName"));//得到省的名字
cmb省.Items.Add(item); //向省中添加Item的内容
}
}
}
}
}
private void cmb省_SelectedIndexChanged(object sender, EventArgs e)
{
cmb市.Items.Clear(); //清除市里边的旧数据
provinceItem item = (provinceItem)cmb省.SelectedItem;
int proID = item.Id; //得到学则省的Id
string cnonStr = ConfigurationManager.ConnectionStrings["connStr"].ConnectionString;
using (SqlConnection conn = new SqlConnection(cnonStr))
{
conn.Open();
using (SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = "select * from city where proID=@proID";
cmd.Parameters.Add(new SqlParameter("proID", proID));//后边的这个proID是选择省的ID
using (SqlDataReader reader = cmd.ExecuteReader())
{
while (reader.Read()) //对于每一条取出cityname
{
string cityname = reader.GetString(reader.GetOrdinal("cityName"));
cmb市.Items.Add(cityname);
}
}
}
}
}
}
class provinceItem
{
public string Name { get; set; }
public int Id { get; set; }
}
}

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