HTML Code<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Index.aspx.cs" Inherits="Index" %>
<%@ Register Assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
Namespace="System.Web.UI" TagPrefix="asp" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>验证用户名是否存在</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
</div>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:TextBox ID="tb_username" runat="server" Width="85px" AutoPostBack="True" OnTextChanged="tb_username_TextChanged"></asp:TextBox>
<asp:Label ID="lb_info" runat="server" Width="76px"></asp:Label>
<asp:TextBox ID="tb_Pwd" runat="server" Width="85px" TextMode="Password"></asp:TextBox><br />
<asp:Button ID="Button1" runat="server" Text="注册" OnClick="Button1_Click" />
</ContentTemplate>
</asp:UpdatePanel>
</form>
</body>
</html>
ASP.NET Code
using System;
using System.Data;
using System.Configuration;
using System.Collections;
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 Index : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!this.IsPostBack)
{
ScriptManager1.SetFocus("tb_username");
}
}
private bool CheckUser()
{
int count = 0;
SqlConnection conn = new SqlConnection("server=.;uid=sa;pwd='';database=UserInfo");
string username = this.tb_username.Text;
string strsql = "select count(uid) from userinfo where username='"+username+"'";
SqlCommand cmd = new SqlCommand(strsql,conn);
conn.Open();
count = (int)cmd.ExecuteScalar();
conn.Close();
if (count == 0)
{
return true;
}
else
{
return false;
}
}
protected void Button1_Click(object sender, EventArgs e)
{
if (!CheckUser())
{
this.lb_info.Text = "用户名已经存在";
ScriptManager.RegisterStartupScript(this.UpdatePanel1, UpdatePanel1.GetType(), "", "document.getElementById('tb_username').select();", true);
}
else
{
lb_info.Text = "注册成功";
}
}
protected void tb_username_TextChanged(object sender, EventArgs e)
{
this.lb_info.Text="";
if (this.CheckUser())
{
this.lb_info.Text = "用户名可以使用";
ScriptManager1.SetFocus("tb_Pwd");
}
else
{
this.lb_info.Text = "用户名已经存在，请重新注册！";
}
}
}