Form - button group with same "name" value - php

Question

I tried to make form with some inputs that insert data in my database, the problem is - one of inputs (button group with name "priority" can't be find by PHP interpreter. Where I should put that name? I think it was bad... Here is my code:
<form action="" method="post">
<div class="form-group">
<strong><label for="towho">Do kogo:</label></strong>
<select class="form-control" name="towho">
<option> - - - </option>
<!-- Skrypt pobierania danych (username) do Selecta -->
<?php
get_users();
?>
</select>
</div>
<hr></hr>
<div class="form-group">
<label for="usr">Temat:</label>
<input type="text" class="form-control" name="topic">
</div>
<hr></hr>
<div class="form-group" style="padding-top:10px">
<strong><label for="comment">Opis zadania:</label></strong>
<textarea class="form-control" rows="5" name="comment"></textarea>
</div>
<hr></hr>
<center>
<div class="form-group">
<strong><p>Priorytet:</p></strong>
<div class="btn-group btn-group-justified" role="group" aria-label="Justified button group">
<div class="btn-group" role="group">
<input type="button" class="btn btn-danger" value="WYSOKI" name="priority">
</div>
<div class="btn-group" role="group">
<input type="button" class="btn btn-warning" value="ŚREDNI" name="priority">
</div>
<div class="btn-group" role="group">
<input type="button" class="btn btn-success" value="NISKI" name="priority">
</div>
</div>
</div>
</center>
<hr></hr>
<div class="form-group">
<button name="submit" type="worksubmit" class="btn btn-info btn-block">Zaakceptuj</button>
</div>
</form>
And here is my PHP code:
if(isset($_POST['submit'])) {
include 'db.php';
$sf = "INSERT INTO zadania (id, user, tablename, dodano, dokogo, tytul, opis, priorytet, zaakceptowano, status) VALUES (NULL, '".$_SESSION['valid_user']."', 'zadania', '".date('d.m.Y')."', '".$_POST['towho']."', '".$_POST['topic']."', '".$_POST['comment']."', '".$_POST['priority']."', '2018-01-01 1:00:00', 'start')";
mysqli_query($conn,$sf);
echo "Succes";
And everything works fine, only that "priority" doesn't work. It show UNDEFINED INDEX "priority" onto my INPUT query. Also... My buttons can't be wide on whole form, their width is defined by chars, but my intentions were different.

Answer 1

Use JQUERY to change the value of a hidden input field named priority and when either button is pressed change the value.
$(document).ready(function () {
$("#priority1").click(function(){
$("#priority").attr("value", "WYSOKI");
});
$("#priority2").click(function(){
$("#priority").attr("value", "ŚREDNI");
});
$("#priority3").click(function(){
$("#priority").attr("value", "NISKI");
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form action="" method="post">
<div class="form-group">
<strong><label for="towho">Do kogo:</label></strong>
<select class="form-control" name="towho">
<option> - - - </option>
<!-- Skrypt pobierania danych (username) do Selecta -->
<?php
get_users();
?>
</select>
</div>
<hr></hr>
<div class="form-group">
<label for="usr">Temat:</label>
<input type="text" class="form-control" name="topic">
</div>
<hr></hr>
<div class="form-group" style="padding-top:10px">
<strong><label for="comment">Opis zadania:</label></strong>
<textarea class="form-control" rows="5" name="comment"></textarea>
</div>
<hr></hr>
<center>
<div class="form-group">
<strong><p>Priorytet:</p></strong>
<input type="text" value="" id="priority" name="priority" hidden>
<div class="btn-group btn-group-justified" role="group" aria-label="Justified button group">
<div class="btn-group" role="group">
<input type="button" class="btn btn-danger" value="WYSOKI" id="priority1">
</div>
<div class="btn-group" role="group">
<input type="button" class="btn btn-warning" value="ŚREDNI" id="priority2">
</div>
<div class="btn-group" role="group">
<input type="button" class="btn btn-success" value="NISKI" id="priority3">
</div>
</div>
</div>
</center>
<hr></hr>
<div class="form-group">
<button name="submit" type="worksubmit" class="btn btn-info btn-block">Zaakceptuj</button>
</div>
</form>