首先，数据库中所有省市数据存放在China数据库中的Area表中，简单数据自己随便添加！没什么可说的！
比较简陋的运行效果
区域选择.png
SQL语句
/****** Script for SelectTopNRows command from SSMS ******/
USE China;
CREATE TABLE Area
(
AreaId INT PRIMARY KEY IDENTITY(1,1) NOT NULL,
AreaName NVARCHAR(32) NULL,
AreaPid INT NOT NULL
)
数据库数据格式就是这样而已
数据.png
其次，应用程序配置文件中添加数据库连接字符串
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<connectionStrings>
<add name="strConnect" connectionString="server=127.0.0.1;uid=sa;pwd=YUNWEN0305;database=China"/>
</connectionStrings>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2" />
</startup>
</configuration>
数据对象
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ProvinceCitySelected
{
class AreaInfo
{
public int AreaId { get; set; }
public int AreaPid { get; set; }
public string AreaName { get; set; }
public override string ToString()
{
return this.AreaName;
}
}
}
导出数据
private void buttonExport_Click(object sender, EventArgs e)
{
#region 保存文件
string fileName = string.Empty;//保存的文件名
//让用户选择要保存文件的路径
using (SaveFileDialog sfd = new SaveFileDialog())
{
if (sfd.ShowDialog() != DialogResult.OK)
{
return;
}
fileName = sfd.FileName;
}
#endregion
string strConnect = ConfigurationManager.ConnectionStrings["strConnect"].ConnectionString;
using (SqlConnection con = new SqlConnection(strConnect))
{
con.Open();
using (SqlCommand cmd = con.CreateCommand())
{
cmd.CommandText = "select AreaId,AreaName,AreaPid from Area";
using (SqlDataReader reader = cmd.ExecuteReader())
{
string tempLine = string.Empty;
using (StreamWriter writer = new StreamWriter(fileName))
{
while (reader.Read())
{
tempLine = reader["AreaId"] + "," + reader["AreaName"] + "," + reader["AreaPid"];
writer.WriteLine(tempLine);//写入文本文件
}
}
}
}
}
}
实现代码也很简单
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Configuration;
using System.Data.SqlClient;
using System.IO;
namespace ProvinceCitySelected
{
public partial class MainFrm : Form
{
public MainFrm()
{
InitializeComponent();
}
private void MainFrm_Load(object sender, EventArgs e)
{
string strConnect = ConfigurationManager.ConnectionStrings["strConnect"].ConnectionString;
using (SqlConnection con = new SqlConnection(strConnect))
{
con.Open();
using (SqlCommand cmd = con.CreateCommand())
{
cmd.CommandText = @"select AreaId,AreaName,AreaPid from Area where AreaPid=0";
using (SqlDataReader reader = cmd.ExecuteReader())
{
//读取一行数据
while (reader.Read())
{
//把表格数据转换成对象的数据
AreaInfo areaInfo = new AreaInfo();
areaInfo.AreaId = int.Parse(reader["AreaId"].ToString());
areaInfo.AreaPid = int.Parse(reader["AreaPid"].ToString());
areaInfo.AreaName = reader["AreaName"].ToString();
//将省的信息放到ComBox中。ComBox显示信息是Item对象的ToString()
this.comboBoxProvince.Items.Add(areaInfo);
} //end while
}//end using reader
}//end using cmd
}//end using con
//默认选择第一条数据
this.comboBoxProvince.SelectedIndex = 0;
}
private void comboBoxProvince_SelectedIndexChanged(object sender, EventArgs e)
{
AreaInfo provinceInfo = this.comboBoxProvince.SelectedItem as AreaInfo;
//判断是否 拿到的城市为空
if (provinceInfo == null)
{
return;
}
//根据省的ID获取所有的城市信息
//加载数据库中的所有省的数据
string strConnect = ConfigurationManager.ConnectionStrings["strConnect"].ConnectionString;
using (SqlConnection con = new SqlConnection(strConnect))
{
con.Open();
using (SqlCommand cmd = con.CreateCommand())
{
cmd.CommandText = @"select AreaId,AreaName,AreaPid from Area where AreaPid="+provinceInfo.AreaId;
using (SqlDataReader reader = cmd.ExecuteReader())
{
this.comboBoxCity.Items.Clear();
//读取一行数据
while (reader.Read())
{
//把表格数据转换成对象的数据
AreaInfo areaInfo = new AreaInfo();
areaInfo.AreaId = int.Parse(reader["AreaId"].ToString());
areaInfo.AreaPid = int.Parse(reader["AreaPid"].ToString());
areaInfo.AreaName = reader["AreaName"].ToString();
//将省的信息放到ComBox中。ComBox显示信息是Item对象的ToString()
this.comboBoxCity.Items.Add(areaInfo);
} //end while
}//end using reader
}//end using cmd
}//end using con
//默认选择第一条数据
this.comboBoxCity.SelectedIndex = 0;
}
//导出数据
private void buttonExport_Click(object sender, EventArgs e)
{
#region 保存文件
string fileName = string.Empty;//保存的文件名
//让用户选择要保存文件的路径
using (SaveFileDialog sfd = new SaveFileDialog())
{
if (sfd.ShowDialog() != DialogResult.OK)
{
return;
}
fileName = sfd.FileName;
}
#endregion
string strConnect = ConfigurationManager.ConnectionStrings["strConnect"].ConnectionString;
using (SqlConnection con = new SqlConnection(strConnect))
{
con.Open();
using (SqlCommand cmd = con.CreateCommand())
{
cmd.CommandText = "select AreaId,AreaName,AreaPid from Area";
using (SqlDataReader reader = cmd.ExecuteReader())
{
string tempLine = string.Empty;
using (StreamWriter writer = new StreamWriter(fileName))
{
while (reader.Read())
{
tempLine = reader["AreaId"] + "," + reader["AreaName"] + "," + reader["AreaPid"];
writer.WriteLine(tempLine);//写入文本文件
}
}
}
}
}
}
}
}
