how to store answers from an online examination system to database - php

Question

I am creating an online examination system where am fetching questions and answers from database and displays options in radio button. But, the problem is if i click save it just saves one answer not answer from all questions
php codes for fetching questions
$quer=" SELECT * FROM questionset ORDER BY RAND() ";
$query=mysqli_query($sql,$quer);
while($row = mysqli_fetch_array($query))
{
$na= $row['qus'];
$opa= $row['opa'];
$opb= $row['opb'];
$opc= $row['opc'];
$opd= $row['opd'];
echo "<div class='pr3'>";
echo "<div id='question'>";
echo $na;
echo "</div>";
echo "<br/>";
echo "<form name='cart' method='post'>";
echo "<input type='radio' name='ans' value='" . $opa. "' onclick='answ(this.value)' >";
echo $opa;
echo "<br/>";
echo "<input type='radio' name='ans' value='" . $opb. "' onclick='answ(this.value)'>";
echo $opb;
echo "<br/>";
echo "<input type='radio' name='ans' value='" . $opc. "' onclick='answ(this.value)'>";
echo $opc;
echo "<br/>";
echo "<input type='radio' name='ans' value='" . $opd. "' onclick='answ(this.value)'>";
echo $opd;
echo "<br/>";
echo "<input type='text' id='ansval' name='ansval' >";
echo "</form>";
echo " </div>";
}
Javascript that updates just one text box
<script>
function answ(answer) {
document.getElementById("ansval").value = answer;
}
</script>

Answer 1

The radio buttons name are all same for all questions. You have to make the radio buttons names dynamically for each answer set. You can use the following code :
$quer=" SELECT * FROM questionset ORDER BY RAND() ";
$query=mysqli_query($sql,$quer);
while($row = mysqli_fetch_array($query))
{
$questionId = $row['questionId']; //primary key of question table
$na= $row['qus'];
$opa= $row['opa'];
$opb= $row['opb'];
$opc= $row['opc'];
$opd= $row['opd'];
echo "<div class='pr3'>";
echo "<div id='question'>";
echo $na;
echo "</div>";
echo "<br/>";
echo "<form name='cart' method='post'>";
echo "<input type='radio' name='ans<?php echo $questionId; ?>' value='" . $opa. "' onclick='answ(this.value,'<?php echo $questionId; ?>')' >";
echo $opa;
echo "<br/>";
echo "<input type='radio' name='ans<?php echo $questionId; ?>' value='" . $opb. "' onclick='answ(this.value,'<?php echo $questionId; ?>')'>";
echo $opb;
echo "<br/>";
echo "<input type='radio' name='ans<?php echo $questionId; ?>' value='" . $opc. "' onclick='answ(this.value,'<?php echo $questionId; ?>')'>";
echo $opc;
echo "<br/>";
echo "<input type='radio' name='ans<?php echo $questionId; ?>' value='" . $opd. "' onclick='answ(this.value,'<?php echo $questionId; ?>')'>";
echo $opd;
echo "<br/>";
echo "<input type='text' id='ansval<?php echo $questionId; ?>' name='ansval<?php echo $questionId; ?>' >";
echo "</form>";
echo " </div>";
}
And You javascript function will be looks like :
<script>
function answ(answer,qId) {
document.getElementById("ansval"+qId).value = answer;
}
</script>
After the answer submit you can get the submitted values in same way. i.e $_POST['ansval'.$questionId]; Before get the value you have to create another loop to get all question Ids.

Answer 2

ID field must be unique
++$counter;
echo "";
$_POST['ansval1'],$_POST['ansval2'],$_POST['ansval3'].....