AJAX 用户唯一性验证实现代码

作者: 达?矢抾哆拉?
来源: 51数据库
2021-08-22

从数据库my中的username用户表里验证：
checkusername.html：

复制代码代码如下:

 
<!doctype html public "-//w3c//dtd xhtml 1.0 transitional//en" "http://www.w3.org/tr/xhtml1/dtd/xhtml1-transitional.dtd"> 
<html xmlns="http://www.51sjk.com/Upload/Articles/1/0/270/270312_20210708032950833.jpg"> 
<head> 
<meta http-equiv="content-type" content="text/html; charset=utf-8" /> 
<title>无标题文档</title> 
</head> 
<script language="javascript"> 
var xmlhttp; 
function createxmlhttprequest(){ 
if(window.activexobject){ 
xmlhttp = new activexobject("microsoft.xmlhttp"); 
} 
else if(window.xmlhttprequest){ 
xmlhttp = new xmlhttprequest(); 
} 
} 
function send_request(url,data){ 
createxmlhttprequest(); 
xmlhttp.open("post",url,true); 
xmlhttp.onreadystatechange = check_lll; 
xmlhttp.setrequestheader("content-type", "application/x-www-form-urlencoded"); 
xmlhttp.send("username=" + data); 
} 
function check_lll(){ 
if(xmlhttp.readystate == 4){ 
if(xmlhttp.status == 200){ 
alert(xmlhttp.responsetext); 
} 
} 
} 
function check_username(){ 
var f = document.form1; 
var username = f.username.value; 
if(username == ""){ 
alert("null"); 
return false; 
} 
else{ 
send_request("check_it.php",username); 
} 
} 
</script> 
<body> 
<form id="form1" name="form1" method="post" action=""> 
<p> </p><p> 
姓名： <input type="text" name="username" /> 
</p> 
<input type="button" value="check it" onclick="check_username()" /> 
<p> </p> 
<p>  </p> 
</form> 
</body> 
</html> 

check_it.php：

复制代码代码如下:

 
<?php 
$username = $_post["username"]; 
$conn = mysql_connect("localhost:3306","root","123"); 
mysql_select_db("my",$conn); 
$sql = "select * from username where username = '$username'"; 
$result = mysql_query($sql,$conn); 
$num = mysql_fetch_array($result); 
if($num > 0){ 
printf("can't use"); 
} 
else{ 
printf("it can use"); 
} 