I was trying to use jquery for processing data. I am sending form data to  register_process.php and checking username already exist or not. If it exist i need to ask the user to re-enter user id else register the user.

2. submitHandler: function (form) {
3. var data =  $('.register-form').serialize();
4. $.get(
5. 'register_process.php',
6. data,
7. function(data)
8. {
9. $('#result').html(data);
10. },
11. 'html'
12. );
13.            }

on success this will be executed

2. function(data)
3. {
4. $('#result').html(data);
5. },

but what i should send from php file so that i can figure out whether user name already exist or not and how to do that.

Thanks,

Samir