部门(DropDownList)和员工(ListBox)的动态显示(一个部门下的员工).

SQL.TXT

create database departMent

use departMent

create table TDepartMent
(
 depID int primary key,
 depName varchar(30) not null
)

insert into TDepartMent values (1,'教务')
insert into TDepartMent values (2,'后勤中心')
insert into TDepartMent values (3,'办公室')

create table emp
(
  empID int primary key,
  empName varchar(30) not null,
  depID int foreign key references TDepartMent(depID)
)

insert into emp values (1,'陈欧',1)
insert into emp values (2,'李波',1)
insert into emp values (3,'刘昆府',1)
insert into emp values (4,'黄珂',2)
insert into emp values (5,'张则名',2)
insert into emp values (6,'陈程',3)
insert into emp values (7,'李四',3)
--------------------------------------------------------------------------------------------------------------------------------
Default.aspx 页面

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!this.IsPostBack)
        {

            //连接数据库
            SqlConnection con = DB.createConnection();
            con.Open();

            //显示部门信息
            SqlCommand cmd = new SqlCommand("select * from TDepartMent", con);
            SqlDataReader sdr = cmd.ExecuteReader();
            this.ddlDepartMent.DataSource = sdr;
            this.ddlDepartMent.DataTextField = "depName";
            this.ddlDepartMent.DataValueField = "depID";
            this.ddlDepartMent.DataBind();
            sdr.Close();

            //显示员工信息
            SqlCommand cmdemp = new SqlCommand("select * from emp where depID=" + this.ddlDepartMent.SelectedValue, con);
            SqlDataReader sdremp = cmdemp.ExecuteReader();
            while (sdremp.Read())
            {
                this.lBoxemp.Items.Add(new ListItem(sdremp.GetString(1),sdremp.GetInt32(0).ToString()));
            }
            sdremp.Close();

            //关闭连接
            con.Close();
        }
    }
    protected void ddlDepartMent_SelectedIndexChanged(object sender, EventArgs e)
    {  
        //清楚ListBox的内容
        this.lBoxemp.Items.Clear();
        //动态显示员工数据
        SqlConnection con = DB.createConnection();
        con.Open();
        SqlCommand cmd = new SqlCommand("select * from emp where depID=" + this.ddlDepartMent.SelectedValue, con);
        SqlDataReader sdr = cmd.ExecuteReader();
        while (sdr.Read())
        {
         this.lBoxemp.Items.Add(new ListItem(sdr.GetString(1),sdr.GetInt32(0).ToString()));
        }
        sdr.Close();
        //关闭数据库
        con.Close();
    }
}