if(mysqli_num_rows(mysqli_query($conn, 'SELECT * FROM userst WHERE email='.$_POST['email']))==0)
if(mysqli_num_rows(mysqli_query($conn, 'SELECT * FROM userst WHERE email="'.$_POST['email'].'"'))==0)
var $win = $(window);
var $marker = $('#marker');
$win.scroll(function() {
if($win.scrollTop() + $win.height() >= $marker.offset().top) {
$('#message').html('конец');
}else{
$('#message').html('не конец');
}
});