ASP.NET实现级联下拉框效果实例讲解

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用ASP.NET控件实现部门和员工的联动,参考过程如下
效果图: 

Default.aspx代码:

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %> 
 
<!DOCTYPE html> 
 
<html xmlns="http://www.w3.org/1999/xhtml"> 
<head runat="server"> 
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> 
 <title></title> 
</head> 
<body> 
 <form id="form1" runat="server"> 
 <div> 
  
  <asp:DropDownList ID="ddlDep" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ddlDep_SelectedIndexChanged"> 
  </asp:DropDownList> 
  <br /> 
  <asp:ListBox ID="lBoxEmp" runat="server"></asp:ListBox> 
  
 </div> 
 </form> 
</body> 
</html> 

Default.aspx.cs代码:

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Web; 
using System.Web.UI; 
using System.Web.UI.WebControls; 
using System.Data.SqlClient; 
 
public partial class _Default : System.Web.UI.Page 
{ 
 protected void Page_Load(object sender, EventArgs e) 
 { 
  if (!this.IsPostBack) 
  { 
   SqlConnection con = DBCon.createConnection(); 
   con.Open(); 
   //显示部门 
   SqlCommand cmd = new SqlCommand("select * from Tdepartment", con); 
   SqlDataReader sdr = cmd.ExecuteReader(); 
   this.ddlDep.DataSource = sdr; 
   this.ddlDep.DataTextField = "depName"; 
   this.ddlDep.DataValueField = "depID"; 
   this.ddlDep.DataBind(); 
   sdr.Close(); 
   //显示员工 
   SqlCommand cmdEmp =new SqlCommand ("select * from emp where depID=" + this.ddlDep .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 ddlDep_SelectedIndexChanged(object sender, EventArgs e) 
 { 
  this.lBoxEmp.Items.Clear(); 
  SqlConnection con = DBCon.createConnection(); 
  con.Open(); 
  SqlCommand cmdEmp = new SqlCommand("select * from emp where depID=" + this.ddlDep.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(); 
 } 
} 

DBCon.cs代码

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Web; 
using System.Data.SqlClient; 
 
/// <summary> 
/// DBCon 的摘要说明 
/// </summary> 
public class DBCon 
{ 
 public DBCon() 
 { 
  // 
  // TODO: 在此处添加构造函数逻辑 
  // 
 } 
 public static SqlConnection createConnection() 
 { 
  SqlConnection con = new SqlConnection("server=.;database=department;uid=sa;pwd=123456"); 
  return con; 
 } 
} 

使用Asp.net控件实现比较简单,但在大量用户使用的情况下最好不要使用,不断向服务器请求会给服务器带来很大的负担。使用JQuery和ajax实现可以有动态效果,实现过程比较复杂,但有数据缓冲和ajax局部刷新可以减少服务器的负担,JQuery实现级联下拉框效果,参考这篇文章:http://www.jb51.net/article/72366.htm

以上就是ASP.NET实现级联下拉框效果实例讲解,希望大家可以学以致用。