jquery ajax based registration form

Question

Hi

I must now seek help after too many hours of failure.

I'm using a basic registration form with Ajax, but the form is not connecting to the database. I'm obviously overlooking something.

So here's the field i want to validate. obviously, its the username.

Username:<input type="text" name="user" id="user" maxlength="30">
<span id="msgbox" style="display:none"></span>

then i use jquery, here's the code:

$(document).ready(function()
{
    $("#user").blur(function()
    {
        //remove all the class add the messagebox classes and start fading
        $("#msgbox").removeClass().addClass('messagebox').text('Checking...').fadeIn("slow");
        //check the username exists or not from ajax
        $.post("user_availability.php",{ user_name:$(this).val() } ,function(data)
        {
          if(data=='no') //if username not avaiable
          {
              $("#msgbox").fadeTo(200,0.1,function() //start fading the messagebox
            {
              //add message and change the class of the box and start fading
              $(this).html('This User name Already exists').addClass('messageboxerror').fadeTo(900,1);
            });       
          }
          else
          {
              $("#msgbox").fadeTo(200,0.1,function()  //start fading the messagebox
            {
              //add message and change the class of the box and start fading
              $(this).html('Username available to register').addClass('messageboxok').fadeTo(900,1);   
            });
          }

        });

    });
});

and i have this code, user_availability.php:

mysql_connect(localhost,$user,$password);
    or die('There is error to connect to server:-'.mysqli_connect_error());
    $db_selected = mysql_select_db($database);


    $user_name=$_POST['user_name'];

    $sql = "select * from members where username='$user_name'";
    $result = mysql_query($sql);

    while($row = mysql_fetch_assoc($result))   
        {
        $existing_users[] = $row['username'];
        }

if (in_array($user_name, $existing_users))
{
    //user name is not availble
    echo "no";
}
else
{
    //user name is available
    echo "yes";
}

I get no database errors. The form will be more substantial, but I can't get it to work with this field. Any suggestions? Any help? Thanks very much...

Answer 1

Check your query:

 $sql = "select * from members where username='$user_name'";

I this the above query should be:

 $sql = "select * from members where username=$user_name";

Answer 2

Just a nitpick on the select statement. Since you only need to get how many rows exist for the entered username you don't need to do a "select *" as depending on the number of columns in your users table you could be returning quite a bit of data. I would revise your query to be like so:

$sql = "select COUNT(username) from members where username=$user_name";

Then you check to make sure that the result of the query equals zero. If it does then the username is available.

I know that the above wasn't an answer to your question but just thought I would point it out since this looks to be a function that is going to get called a lot depending on the traffic on your registration form and the creativity of your visitors.