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 省市联动
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
Tsql.GetConnection();
using (SqlConnection conn = new SqlConnection(Tsql.GetConnection()))
{
conn.Open();
using (SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = “select * from promary”;
using (SqlDataReader dr = cmd.ExecuteReader())
{
while (dr.Read())
{
Province pr = new Province();
pr.proID = dr.GetInt32(dr.GetOrdinal(“proID”)); //这里要出格注意数据库字段的类型 proID在数据库里是int型
pr.proName = dr.GetString(dr.GetOrdinal(“proName”));
comboBox1.Items.Add(pr);//pr是一个Province东西。Province有一个proName和proID属性。我将一个东西填充到comboBox1里。再让comboBox1的DisplayMember属性设置proName。【也就是让comboBox1显示pr东西的proName属性】。这样在填充市级都市的时候我就可以找到当前选择项comboBox1.SelectedItem（或者当前选择东西）所对应的proID
}
}
}
comboBox1.SelectedIndex = 0; //将comcomboBox1的默认选项设为0
}
}
private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
{
}
private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
comboBox2.Items.Clear(); //在选择的时候先清空一下combox1里面的所以项，，以免在改换省名的时候，与先前对应的省名下的市没有删除。
Province tem = (Province)comboBox1.SelectedItem; // 因为在comboBox1.Items.Add(pr)里添加的是东西。所以在这里讲comBox1所选中确当前东西赋给tem东西 （tem东西下面有两个属性 proName和proID）
int id = tem.proID; //将当前选中东西的的proID赋值给id，给下面的sql盘问语句使用
Tsql.GetConnection();// 获取数据库连接字符串。
using (SqlConnection conn = new SqlConnection(Tsql.GetConnection()))
{
conn.Open();
using (SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = “select * from city where [email protected]”;
cmd.Parameters.Add(new SqlParameter(“id”, id));
using (SqlDataReader dr = cmd.ExecuteReader())
{
while (dr.Read())
{
comboBox2.Items.Add(dr.GetString(dr.GetOrdinal(“cityName”)));
}
}
}
comboBox2.SelectedIndex = 0; //将comcomboBox1的默认选项设为0
}
}
}
class Tsql
{
public static string GetConnection() //数据库连接字符串
{
string getConn = ConfigurationManager.ConnectionStrings[“getConn”].ConnectionString;
return getConn;
}
}
class Province
{
public string proName { get; set; }
public int proID { get; set; }
}
}
代码如下:
using System.Data.SqlClient;
namespace 省市选择2
{
public partial class Form1 : Form
{
publicForm1()
{
InitializeComponent();
}
privatevoid Form1_Load(objectsender,EventArgs e)
{
/*
//测试代码：执行这段代码的情况下是可以吧 tom这个值添加到 comboBox1中的。
People p1 = new People();
p1.name = “tom”;
p1.age = 25;
comboBox1.Items.Add(p1.name);
*/
using(SqlConnection conn =newSqlConnection(“Data source=凡斌-VAIO;Initialcatalog=DBPromary;integrated security=true”))
{
conn.Open();
using(SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = “select * from promary”;
using(SqlDataReader reader = cmd.ExecuteReader())
{
while (reader.Read())
{
//string str =reader.GetString(reader.GetOrdinal(“proName”));
//comboBox1.Items.Add(str);
Province pv =new Province();
//将comboBox1控件的DisplayMember属性设置为“ProvinceName”用来在comboBox1控件中显示ProvinceName属性的值
comboBox1.DisplayMember = “ProvinceName”;
pv.ProvinceName =reader.GetString(reader.GetOrdinal(“proName”));
pv.ProvinceID =reader.GetInt32(reader.GetOrdinal(“proID”));
//虽然pv属于东西，把一个东西添加到ComboxBox1中，控件显示的值为东西的类名，但是在前面comboBox1.DisplayMember =”ProvinceName”处已经设置好控件要显示的为 Province类的ProvinceName值，所以添加进去的是pv东西的ProvinceName值
comboBox1.Items.Add(pv);
}
}
}
}
}