departments show in combobox,then show employee info. of the related department

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;
using System.Data.SqlClient;
namespace Test
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        string connStr = @"Data Source=YOUSEF-PC\SQLEXPRESS;Initial Catalog=Northwind;Integrated Security=True";
        private void Form1_Load(object sender, EventArgs e)
        {
            SqlConnection conn = new SqlConnection();
            conn.ConnectionString = connStr;
            conn.Open();
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = conn;
            cmd.CommandType = CommandType.Text;
            cmd.CommandText = "select distinct city  from employees";
            SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
            while (reader.Read())
            {
                lstDepartments.Items.Add(reader["city"].ToString());
            }
            conn.Close();
        }
        
        private void lstDepartments_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (lstDepartments.SelectedText!=null)
            {
                lstEmployees.Items.Clear();
                SqlConnection conn = new SqlConnection();
                conn.ConnectionString = connStr;
                conn.Open();
                SqlCommand cmd = conn.CreateCommand();
                cmd.CommandText = "select (firstname +' '+lastname) as fullname from employees where dept=@dept";
                cmd.Parameters.AddWithValue("@dept", lstDepartments.SelectedText);
                SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                lstEmployees.BeginUpdate();
                while (reader.Read())
                {
                    lstEmployees.Items.Add(reader[0].ToString());
                }
                lstEmployees.EndUpdate();
                conn.Close();
            }
        }
    }
}

Hi,
One solution is using a GridView and change GridView data source based on selected dropdownlist value. You will get implementation details from this link below
http://forums.asp.net/t/1588209.aspx[^]
Hope this will help.

You cannot file the solution because your choice of ComboBox is not adequate to the structure you need to show. For such purpose the TreeView would serve the best.

Alternative solution would be two combo boxes (each of them or both could be also a ListBox): one of them represents the name of department, another one — items withing the department. In this case, change in selection of the first box should re-populate the second one.

—SA