下拉列表联动

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;

namespace t4_下拉列表联动
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

private void Form1_Load(object sender, EventArgs e)
{
BindCompany();
}
private void BindCompany()
{
//清空原有数据
cboCompany.Items.Clear();
cboCompany.Items.Add("-请选择-");
cboCompany.SelectedIndex = 0;
//数据数据库表中的内容,完成绑定
string connStr = System.Configuration.ConfigurationManager.ConnectionStrings["hem09"].ConnectionString;
using (SqlConnection conn = new SqlConnection(connStr))
{
string sql = "select * from groups where gparent=1";
SqlCommand cmd = new SqlCommand(sql, conn);
conn.Open();
SqlDataReader reader = cmd.ExecuteReader();
while (reader.Read())
{
Groups g = new Groups() { Gid = reader.GetInt32(0), Gname = reader.GetString(1) };
cboCompany.Items.Add(g);
cboCompany.DisplayMember = "gname";
}
reader.Close();
reader.Dispose();
}
}
private void BindDepart(int comID)
{
cboDepart.Items.Clear();
cboDepart.Items.Add("-请选择-");
cboDepart.SelectedIndex = 0;

string connStr = System.Configuration.ConfigurationManager.ConnectionStrings["hem09"].ConnectionString;
using (SqlConnection conn = new SqlConnection(connStr))
{
//string sql = "select * from groups where gparent=" + comID;
string sql = "select * from groups where gparent=@comID";
SqlCommand cmd = new SqlCommand(sql, conn);
cmd.Parameters.Add(new SqlParameter("@comID", comID));
conn.Open();
using (SqlDataReader reader = cmd.ExecuteReader())
{
while (reader.Read())
{
Groups g = new Groups() { Gid=reader.GetInt32(0),Gname=reader.GetString(1)};
cboDepart.Items.Add(g);
cboDepart.DisplayMember = "gname";
}

}
}
}
private void cboCompany_SelectedIndexChanged(object sender, EventArgs e)
{
//获取选中项
Groups g = cboCompany.SelectedItem as Groups;
if (g != null)
{//如果选择了某个公司,则加载这个公司的部门信息
BindDepart(g.Gid);
}
else
{//用户选择了"请选择"
cboDepart.Items.Clear();
}
}
}
}