namespace 省市選擇
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

private void Form1_Load(object sender, EventArgs e)
{
string connstr=ConfigurationManager.ConnectionStrings["ConnStr"].ConnectionString;
using (SqlConnection conn = new SqlConnection(connstr))//使用配置文件的方法建立連接

// using (SqlConnection conn = new SqlConnection(@"Data Source=.\sqlexpress;
// AttachDbFilename=|DataDirectory|\ss.mdf;
// Integrated Security=True;User Instance=True"))
{
conn.Open();
using (SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = "select * from promary";

using (SqlDataReader dataReader = cmd.ExecuteReader())
{
while (dataReader.Read())
{
ProvinceItem item = new ProvinceItem();
item.Id = dataReader.GetInt32(dataReader.GetOrdinal("proID"));
item.Name = dataReader.GetString(dataReader.GetOrdinal("proName"));
cmb省.Items.Add(item);
}
}
}
}

}

private void cmb省_SelectedIndexChanged(object sender, EventArgs e)
{
cmb市.Items.Clear();//清除舊數(shù)據(jù)
ProvinceItem item = (ProvinceItem)cmb省.SelectedItem;
int proID = item.Id;

string connstr = ConfigurationManager.ConnectionStrings["ConnStr"].ConnectionString;
using (SqlConnection conn = new SqlConnection(connstr))//使用配置文件的方法建立連接

// using (SqlConnection conn = new SqlConnection(@"Data Source=.\sqlexpress;
// AttachDbFilename=|DataDirectory|\ss.mdf;
// Integrated Security=True;User Instance=True"))
{

conn.Open();

using (SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = "select * from city where proID=@proID";
cmd.Parameters.Add(new SqlParameter("proID", proID));

using (SqlDataReader dataReader = cmd.ExecuteReader())
{

while (dataReader.Read())
{
string cityName = dataReader.GetString(dataReader.GetOrdinal("cityName"));
cmb市.Items.Add(cityName);
}
}
}
}
}

}
}
class ProvinceItem
{
public string Name { get; set; }
public int Id { get; set; }
}

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轉(zhuǎn)載于:https://www.cnblogs.com/zwjblogs/archive/2012/03/03/2378086.html

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