basic multiple answers quiz system checkbox ambiguity - php

Question

I am trying to build a basic quiz system and everything seems ok.
The following code shows how a users choose the correct answer and the getresult.php shows the result. In my database, there is a question, opt1, opt2, opt3 opt4 and answer column.
<form method="POST" action="getresult.php">
<label>Enter Your Name:</label><br>
<input type="text" name="name" required><br><br>
<?php
$db = new mysqli("localhost", "root", "","learndb");
$stmt=$db->prepare("SELECT * FROM quiz");
$stmt->execute();
$result=$stmt->get_result();
while($myrow = $result->fetch_assoc())
{
echo "<form method='POST' action='getresult.php'>";
echo $myrow['id'];
echo ".";
echo $myrow['question'];
echo "<br>";
echo "<input type='checkbox' name='mycheck[]' value=".$myrow['opt1'].">";
echo $myrow['opt1'];
echo "<br>";
echo "<input type='checkbox' name='mycheck[]' value=".$myrow['opt2'].">";
echo $myrow['opt2'];
echo "<br>";
echo "<input type='checkbox' name='mycheck[]' value=".$myrow['opt3'].">";
echo $myrow['opt3'];
echo "<br>";
echo "<input type='checkbox' name='mycheck[]' value=".$myrow['opt4'].">";
echo $myrow['opt4'];
echo "<br><br>";
}
?>
<input type="submit" name="submit" value="Get Results" class="btn btn-primary">
getresult.php
<?php
extract($_POST);
$db = new mysqli("localhost", "root", "","learndb");
$stmt=$db->prepare("SELECT * FROM quiz");
$stmt->execute();
$result=$stmt->get_result();
$myrow = $result->fetch_assoc();
$totalCheckboxChecked = sizeof($_POST['mycheck']);
$submit=isset($_POST['submit']);
$count=0;
if($submit)
{
for($i=0;$i<$totalCheckboxChecked;$i++)
{
if($mycheck[$i]==$myrow['answer'])
{
$count=$count+1;
}
}
echo "Hello ";
echo $_POST['name'];
echo "<br>";
echo "You scored ";
echo $count;
}
Now the problem is with the checkbox, I can check all the values from all the questions. And when I use radio button I can check only one value from all questions. How can I check only one value from one question.

Answer 1

I don't know why you're not using radio buttons if you plan to allow only one selection, but you can set a limit to have the same thing with checkboxes with some JavaScript (or jQuery).
Here is an example: see fiddle demo
var limit = 1;
$('input').on('change', function(event) { // this could've been a 'click' event too.
if($(this).siblings(':checked').length >= limit) {
this.checked = false;
/* OR you can do like:
if($("input[name='mycheck']:checked").length > limit) { //... }
*/
}
});

Answer 2

if the question contain only one answer better use radio buttons to select the option
or
else
use this jquery to select single value from checkbox
$('input[type="checkbox"]').on('change', function() {
$('input[type="checkbox"]').not(this).prop('checked', false);
});