php ajax注册验证用户名是否存在代码_php教程

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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php ajax注册验证用户名是否存在代码