php ajax注册验证用户名是否存在代码
这是注册程序是一款当用户输入完用户名是，就会自动去数据库中查询用户要注册的用户名是否己经被注册了，如果是返回提示否则提示可以注册。
conn.php文件
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<script >
var xmlhttp
function showhint(str) {
if (str.length == 0) {
document.getelementbyid("txthint").innerhtml = ""
return
}
xmlhttp = getxmlhttpobject()
if (xmlhttp == null) {
alert("browser does not support http request")
return
}
xmlhttp.onreadystatechange = statechanged
var geturl = "conn.php?q=" + str
//sid是增加一个随机数 防止页面启用缓存技术·
geturl = geturl + "&sid=" + math.random()
geturl = encodeuri(geturl);
geturl = encodeuri(geturl);
xmlhttp.open("get", geturl, true)
xmlhttp.send(null)
}
function statechanged() {
if (xmlhttp.readystate == 4 || xmlhttp.readystate == "complete") {
document.getelementbyid("txthint").innerhtml = xmlhttp.responsetext
}
}
function getxmlhttpobject() {
var xmlhttp = null;
try {
// firefox, opera 8.0+, safari
xmlhttp = new xmlhttprequest();
} catch (e) {
// internet explorer
try {
xmlhttp = new activexobject("msxml2.xmlhttp");
} catch (e) {
xmlhttp = new activexobject("microsoft.xmlhttp");
}
}
return xmlhttp;
}
</script>
</head>
<body bgcolor="#999999">
<center>
<form>
<table>
<tr>
<td>用户名：</td>
<td><input type="text" id="txt1" onkeyup="showhint(this.value)"></td>
</tr>
<tr align="center">
<td colspan="2"><span id="txthint"></span></td>
</tr>
</table>
</form>
</center>
</body>
</html>
<?php
$q = $_get["q"];
$q = urldecode($q);
if (strlen($q) > 0) {
$conn = @mysql_connect("localhost", "root", "1010") or die("mysql连接错误");
mysql_select_db("xin", $conn);
mysql_query("set names 'utf8'");
$sql = "select username from message where username = '$q'";
$query = mysql_query($sql);
@$row = mysql_fetch_array($query);
if (!emptyempty($row['username'])) {
$response = "<font color=red>已经被注册！</font>";
} else {
$response = "<font color=blue>恭喜！可以注册！</font>";
}
echo $response;
}
?>数据库
drop database if exists `xin`; create database `xin` /*!40100 default character set utf8 */; use `xin`; create table `message` ( `id` int(11) not null auto_increment, `username` varchar(20) default null, primary key (`id`) ) engine=innodb auto_increment=2 default charset=utf8;
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