how to implement ajax in php

vikranth

hi, i am doing a mini project in php. In this, i have a customer registration form and the customer has to enter a desired user name for their login and click on a button named 'check availability' to check whether the username is available or not. when clicking that button, the entire page refreshes. instead how to use ajax to refresh that particular part of the page alone.

NOTE : I am using mysql database and when i click on the 'check availability' button i have to check the database to know whether the username already exists or not. if the username already exists i have to display an error message stating "username already exists" otherwise i have to display a message "username is available"
pls anyone help me
waiting for the suggestions

sana

Hello,

On the onClick event of the button make a ajax call to the server to check the

validity... You can also show validating gif image till u get the response.

Regards,

Sana

vikranth

Thank you sana, but a sample coding of both ajax and php will help me to understand better

NogDog

W3Schools PHP/AJAX tutorial

sana

Hi vikranth,

Hope this may help you.....

<html>
    <head>
        <script type="text/javascript">
            function checkExist()
            {
                name= document.getElementById("uname").value;
                if (name.length==0)
                {
                    document.getElementById("errormsg").innerHTML="Enter name to validate";
                    return;
                }
                if (window.XMLHttpRequest)
                {// code for IE7+, Firefox, Chrome, Opera, Safari
                    xmlhttp=new XMLHttpRequest();
                }
                else
                {// code for IE6, IE5
                    xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
                }
                xmlhttp.onreadystatechange=function()
                {
                    if (xmlhttp.readyState==4 && xmlhttp.status==200)
                    {
                        document.getElementById("errormsg").innerHTML=xmlhttp.responseText;
                    }
                }
                xmlhttp.open("GET","Validator.php?uname="+name,true);
                xmlhttp.send();
            }
        </script>
    </head
    <body>

    <p><b>Start typing a name in the input field below:</b></p>
    <form> 
        User name: <input type="text" id="uname" size="20" />
        <input type="button" value="check availability" onclick="checkExist()"/>
    </form>
    <p><span id="errormsg"></span></p>

</body>
</html>

Validator.php

<?php
defined('DB_SERVER')?null:define("DB_SERVER", "localhost");
defined('DB_USER')?null:define("DB_USER", "root");
defined('DB_PASS')?null:define("DB_PASS", "");
defined('DB_NAME')?null:define("DB_NAME", "dummy");




if(isset ($_GET['uname']))
{
    $connection= mysql_connect(DB_SERVER, DB_USER,DB_PASS) or die("Database connection failed:".mysql_error());

$db_select=mysql_select_db(DB_NAME, $connection) or die("Database selection failed:" .mysql_error());

$sql="SELECT uname FROM users WHERE uname='".$_GET['uname']."'";
$result=mysql_query($sql)or die(); ;
$r=mysql_fetch_object($result);
if(empty ($r->uname))
        echo "Not available";
else
     echo "Name already exists";
}
?>

Regards,

Sana

vikranth

Thanks a lot sana, it works well.. thank you...