//第一步:新建一个（*.aspx|*.html)Index.aspx页面 添加jquery
1 <html xmlns="http://www.w3.org/1999/xhtml">
2 <head runat="server">
3 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
4 <title>检测用户名是否存在</title>
5 <script type="text/javascript" src="js/jquery-1.9.1.js"></script>
6 <script type="text/javascript">
7 function UserName() {
8 $.ajax({
9 type: "GET",
10 url: "Index.ashx",
11 dataType: "html",
12
13 data: "userName=" + $("#txtName").val(),
14 beforeSend: function (XMLHttpRequest) {
15 $("#showResult").text("正在查询...");
16 },
17 success: function (msg) {
18 $("#showResult").html(msg);
19 $("#showResult").css("color", "red");
20 },
21 complete: function (XMLHttpRequest, textStatus) {
22 //隐藏正在查询图片
23 },
24 error: function () {
25 //错误处理
26 }
27 });
28 }
29
30 </script>
31
32 </head>
33 <body>
34 <form id="form1" runat="server">
35 <div>
36 <input id="txtName" type="text" /><input type="button" value="检测" id="btn" onclick="UserName();" />
37 <div id="showResult" style="float: left"></div>
38 </div>
39 </form>
40 </body>
41 </html>
第二步:新建一个处理界面Index.ashx
1 public void ProcessRequest(HttpContext context)
2 {
3 context.Response.ContentType = "text/html";
4 string userName = context.Request.QueryString["userName"].Trim().ToString();
5 DataTable dt = SqlHelper.ExecuteDataTable("select * from dbo.T_Login where UseName=@UseName",
new SqlParameter("@UseName", SqlDbType.NVarChar) { Value = userName });
6 //判断表不能为空
7 DataRow dr = null;
8 if (dt != null && dt.Rows.Count > 0)
9 { dr = dt.Rows[0];
10 if (userName ==dr["UseName"].ToString())
11 {
12 context.Response.Write("用户名已经存在！");
13 }
14 else
15 {
16 context.Response.Write("您可以使用此用户名！");
17 }
18 }
19 else
20 {
21 context.Response.Write("您可以使用此用户名！");
22 }
23 }