show and hide required form with a condition - php

Question

I have a task where a form will appear when the star rating is below 3 and must be filled (required). but if the star rating is above 3 then the form does not need to appear and does not need to be filled.
the form is hidden and displayed when the star value below 3 is
<div id="masukan">
<label>Masukan Untuk Kami </label>
<textarea name="masukan" id="masukan" class="form-control" placeholder="Kritik Dan Saran Membangun Anda" required=""></textarea></div>
because the logic is when the rating is below 3 users must fill in the form (show) and if the rating is above 3 users do not have to fill in the form (hide). the problem is when saving to the database where the user gives a 3 star rating.
the code that I now have is like this:
<div id="add_data_Modal" class="modal fade">
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<h4 class="modal-title">Berikan Pendapatmu Tentang Bagaimana Kami !!</h4>
</div>
<div class="modal-body">
<form method="post" id="insert_form">
<label>Tanggal Lahir</label>
<input type="date" name="tgl_lahir" id="tgl_lahir" class="form-control" value="Tanggal Lahir Anda !" required="" />
<br />
<label>Pekerjaan</label>
<input type="text" name="pekerjaan" id="pekerjaan" class="form-control" placeholder="Tuliskan Pekerjaan Utama Anda!" required="" />
<br />
<label>Rating Kepuasan</label><br/>
<fieldset id='demo3' class="rating">
<input class="stars" type="radio" id="star53" name="rating" value="5" />
<label class = "full" for="star53" title="5 Bintang"></label>
<input class="stars" type="radio" id="star4half3" name="rating" value="4.5" />
<label class="half" for="star4half3" title="4,5 Bintang"></label>
<input class="stars" type="radio" id="star43" name="rating" value="4" />
<label class = "full" for="star43" title="4 Bintang"></label>
<input class="stars" type="radio" id="star3half3" name="rating" value="3.5" />
<label class="half" for="star3half3" title="3,5 Bintang"></label>
<input class="stars" type="radio" id="star33" name="rating" value="3" />
<label class = "full" for="star33" title="3 Bintang"></label>
<input class="stars" type="radio" id="star2half3" name="rating" value="2.5" />
<label class="half" for="star2half3" title="2,5 Bintang"></label>
<input class="stars" type="radio" id="star23" name="rating" value="2" />
<label class = "full" for="star23" title="2 Bintang"></label>
<input class="stars" type="radio" id="star1half3" name="rating" value="1.5" />
<label class="half" for="star1half3" title="1,5 Bintang"></label>
<input class="stars" type="radio" id="star13" name="rating" value="1" />
<label class = "full" for="star13" title="1 Bintang"></label>
<input class="stars" type="radio" id="starhalf3" name="rating" value="0.5" />
<label class="half" for="starhalf3" title="0,5 Bintang"></label>
</fieldset>
<br />
<br />
<div id="masukan">
<label>Masukan Untuk Kami </label>
<textarea name="masukan" id="masukan" class="form-control" placeholder="Kritik Dan Saran Membangun Anda" required=""></textarea></div>
<br />
<label>Email Anda</label><br/>
<input type="text" name="email_member" id="email_member" class="form-control" readonly value="<?php echo $email_member;?>" />
<br />
<br/>
<input type="submit" name="insert" id="insert" value="Insert" class="btn btn-success" />
</form>
</div>
</div>
</div>
</div>
<script>
$(document).ready(function(){
$('#insert_form').on("submit", function(event){
event.preventDefault();
if($('#tgl_lahir').val() == "")
{
alert("Tanggal Lahir harus di isi");
}
else if($('#pekerjaan').val() == '')
{
alert("Pekerjaan harus di isi");
}
else
{
$.ajax({
url:"insert.php",
method:"POST",
data:$('#insert_form').serialize(),
beforeSend:function(){
$('#insert').val("Inserting");
},
success:function(data){
$('#insert_form')[0].reset();
$('#add_data_Modal').modal('hide');
$('#employee_table').html(data);
}
});
}
});
});
$('input[type=radio][name=rating]').change(function() {
if ($(this ).val() <=3) {
$ ('#masukan').show();
}
else {
$('#masukan').hide();
}
});
</script>
and this proses.php
<?php
include"page/koneksi.php";
try{
$tgl_lahir = $_POST["tgl_lahir"];
$pekerjaan = $_POST["pekerjaan"];
$rating = $_POST["rating"];
$masukan = $_POST["masukan"];
$email_member = $_POST["email_member"];
if (isset($tgl_lahir) AND isset($pekerjaan) AND isset($rating) AND isset($masukan) AND isset($email_member)) {
$query = $db_con->prepare("insert into tb_voting (tgl_lahir,pekerjaan,kepuasan,masukan,email_member)
values ('$tgl_lahir','$pekerjaan','$rating','$masukan','$email_member')"); }
$query->execute($_POST);
echo "Data telah disimpan";
}catch(PDOException $e){
echo "Error! gagal menyimpan:".$e->getMessage();
}
?>