building an evaluation form php - php

Question

I'm trying to create an evaluation form for students, all questions are stored in db. I'm retrieving them from db any trying to store the answers for each question on db again. all answers should be selected from radio buttons as the following:
<?php
$sql = "SELECT Q_body, Q_ID FROM s_evaluation_questions WHERE Ev_ID='1'";
$result = $conn->query($sql);
?>
<?php
if ($result->num_rows > 0)
{
?>
<form action="AnswerS.php" method="POST">
<table align="right" id="keywords" cellspacing="0" cellpadding="0">
<thead>
<tr>
<th colspan="4"> </th>
<th>Question</th>
</tr>
</thead>
<tbody>
<?php
while($row = $result->fetch_assoc())
{ $answer="s".$row["Q_ID"];
?>
<tr>
<td>
<input type="hidden" name="Q_ID" value="<?php echo $row["Q_ID"]; ?>" >
<input type="radio" name=<?php echo $answer?> value="Bad" >Bad
<input type="radio" name=<?php echo $answer?> value="Good"> Good
<input type="radio" name=<?php echo $answer?> value="VeryGood"> Very Good
<input type="radio" name=<?php echo $answer?> value="Excellent"> Excellent</td>
<td align="right"> <?php echo $row["Q_body"]?></td>
</tr>
<?php } ?>
</tbody>
</table></br></br></br></br></br></br></br>
<input type="submit" value="Send" />
</form>
<?php
?></div>
<?php
} else
{echo "not allowed";}
And on the AnswerS.php page I suppose to store the answers on db as the following:
$UID='1';
$answer=$_POST['answer'];
$Q_ID= $_POST['Q_ID'];
$sql = "INSERT INTO s_evaluation_answers(Q_ID, A_body, UID) VALUES($Q_ID, $answer, $UID) ";
$result = $conn->query($sql);
if ($result === TRUE) {
echo "done" ;
}
else {
echo "Error: " . $sql . "<br>" . $conn->error;
}
but unfortunately it doesn't work!, I tried to trace the value of Q_ID and it gives only the last question id not all questions.
how can I store the selected value from the radio button for each question and store it as the answer for this question? (note: all questions are brought from db)
thanks

Answer 1

If you see your source html you will find that you have many fields with name Q_ID:
<input type="hidden" name="Q_ID" value="one id" >
<input type="hidden" name="Q_ID" value="another id" >
<input type="hidden" name="Q_ID" value="some more id" >
So browser sends you the last value of Q_ID - in above case it is some more id.
To avoid this - use [] notation in name attribute:
<input type="hidden" name="Q_ID[]" value="one id" >
<input type="hidden" name="Q_ID[]" value="another id" >
<input type="hidden" name="Q_ID[]" value="some more id" >
After that, outputting $_POST['Q_ID'] will give you an array. You can iterate over it with foreach and gather other info you need. Something like (simplified):
foreach ($_POST['Q_ID'] as $q) {
// answer will be stored in a `s . $q` value of POST
$answer = $_POST['s' . $q];
$sql = "INSERT INTO s_evaluation_answers(Q_ID, A_body, UID) VALUES($q, $answer, $UID) ";
$result = $conn->query($sql);
}