Ajax php user login example without refresh_PHP tutorial

<script><br> function userlogin(){<br>     var xmlhttp;<br>     var str;<br>     var sendstr="";<br>      try{<br>              xmlhttp=new xmlhttprequest();<br>          }<br>  catch(e){<br>              xmlhttp=new activexobject("microsoft.xmlhttp");<br>         }<br>  xmlhttp.onreadystatechange=function(){<br>           if (xmlhttp.readystate==4){<br>               if (xmlhttp.status==200){  <br>       str = xmlhttp.responsetext;  <br>       document.getelementbyid("userlogin").innerhtml=str; <br>       }else{<br>       alert("系统错误,如有疑问,请与管理员联系!"+xmlhttp.status);<br>     }<br>           }<br>        }<br>  xmlhttp.open("post","config/userlogin.php",true);<br>  xmlhttp.setrequestheader('content-type','application/x-www-form-urlencoded');<br>  xmlhttp.send(sendstr); <br>  }<br> </script>

 

   
   


  输入用户名

 

   
 

userlogin.php文件

$uid = $_post['uname'];
$pwd = $_post['upwd'];
$sql ="select * from tabname where uid='$uid' and pwd='$pwd'";
$query = mysql教程_query( $sql );
if( mysql_num_rows( $query ) )
{
    echo '登录成功';
 }
 else
 {
     echo '用户名或密码不正确!';
  }
?>