<%@ Page Language="C#" AutoEventWireup="true" CodeFile="regdemo.aspx.cs" Inherits="regdemo" %> <!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> <script type="text/javascript"> function loadXMLDoc() { var xmlhttp; if (window.XMLHttpRequest) {// code for IE7+, Firefox, Chrome, Opera, Safari xmlhttp = new XMLHttpRequest(); } else {// code for IE6, IE5 xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); } xmlhttp.onreadystatechange = function () { if (xmlhttp.readyState == 4 && xmlhttp.status == 200) { document.getElementById("myuser").innerHTML = xmlhttp.responseText; } } xmlhttp.open("GET", "./ajax/checkuser.aspx?username="+ document.getElementById(‘Text1‘).value +"", true); xmlhttp.send(null); } </script> </head> <body> <form id="form1" runat="server"> <div> 用户: <input id="Text1" type="text" onchange ="loadXMLDoc()" /><label id="myuser" style="color:red;"></label><br /> <br /> 密码: <input id="Text2" type="text" /> </div> </form> </body> </html>
using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using CnxinwaDll; public partial class ajax_checkuser : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { if (Request["username"].ToString() == "") { Response.Write("用户名不能为空"); Response.Flush(); Response.End(); } else if (isexit(Request["username"].ToString())) { Response.Write("用户名存在,不可以注册:" + Request["username"].ToString()); Response.Flush(); Response.End(); } else if (!isexit(Request["username"].ToString())) { Response.Write("用户名不存在,可以注册:" + Request["username"].ToString()); Response.Flush(); Response.End(); } } /// <summary> /// 验证用户账号是否存在,存在返回TRUE否则返回FALSE /// </summary> /// <param name="uname"></param> /// <returns></returns> protected Boolean isexit(string uname) { Data.sqlstr = "select c003 from cnxinwa002 where c002=‘" + uname + "‘ "; if (Data.GetDataSet(Data.sqlstr).Tables[0].Rows.Count > 0) { return true; } else { return false; } } }
原文：http://www.cnblogs.com/cnxinwa/p/3558874.html