Why is that My PHP records not being INSERTED - php

Question

Good Day!
Guys can you help me to check why my is it that i cannot insert records using chekbox option on table..
Please Help..
Here's My Code...
--ADDING Subject Load for Teacher HTML Form-- (studsub.php)
<form action="setsubject.php" method="post">
<?php
include('../connect.php');
$id=$_GET['id'];
$result = mysql_query("SELECT * FROM student WHERE id='$id'");
while($row = mysql_fetch_array($result))
{
//$course=$row['course'];
//$year=$row['yearlevel'];
//$section=$row['section'];
$idnumber=$row['idnumber'];
echo '<br/>';
echo $row['lname'].", ".$row['fname'];
?>
<input type="hidden" name="studidnum" value="<?php echo $rows['idnumber']?>">
<?php }
?>
<br/><br/>
<label for="filter">Filter</label> <input type="text" name="filter" value="" id="filter" />
<table cellpadding="1" cellspacing="1" id="resultTable">
<thead>
<tr>
<th style="border-left: 1px solid #C1DAD7"><label>Assign</label></th>
<th style="border-left: 1px solid #C1DAD7"> Subject ID </th>
<th>Title</th>
<th>Units</th>
</tr>
</thead>
<tbody>
<?php
include('../connect.php');
$result = mysql_query("SELECT * FROM tbl_cur_sub where status='1' ");
while($row = mysql_fetch_array($result))
{
echo '<tr class="record">';
echo ' <td>' . '<input type="checkbox" name="subject[]" value="'.$rows['code'].'" />' . '</td> ' ;
echo '<td style="border-left: 1px solid #C1DAD7">'.$row['code'].'</td>';
echo '<td><div align="left">'.$row['subject'].'</div></td>';
echo '<td><div align="left">'.$row['units'].'</div></td>';
echo '</tr>';
}
?>
</tbody>
</table>
<br/>
Course<br>
<select name="course" class="ed">
<?php
include('../connect.php');
$results = mysql_query("SELECT * FROM course");
while($rows = mysql_fetch_array($results))
{
echo '<option>'.$rows['coursecode'].'</option>';
}
?>
</select>
<select name="yearlevel" class="ed">
<?php
include('../connect.php');
$results = mysql_query("SELECT * FROM tbl_yrlevel");
while($rows = mysql_fetch_array($results))
{
echo '<option>'.$rows['yearlevel'].'</option>';
}
?>
</select>
<select name="section" class="ed">
<option>A</option>
<option>B</option>
<option>C</option>
<option>D</option>
</select>
<br>
<br>
<input type="submit" value="Assign" id="button1">
</form>
--The Submission Page -- (setsubject.php)
<?php
include('../connect.php');
//Function to sanitize values received from the form. Prevents SQL injection
function clean($str)
{
$str = #trim($str);
if(get_magic_quotes_gpc())
{
$str = stripslashes($str);
}
return mysql_real_escape_string($str);
}
//Sanitize the POST values
$course = clean($_POST['course']);
$section = clean($_POST['section']);
$yearlevel = clean($_POST['yearlevel']);
$studidnum=$_POST['studidnum'];
$subject=$_POST['subject'];
$N = count($subject);
for($i=0; $i < $N; $i++)
{
mysql_query("INSERT INTO studentsubject (student, subject, section, course, level) VALUES ('$studidnum', '$subject[$i]','$section','$course', '$level')");
}
header("location: student.php");
mysql_close($con);
?>
--My Database--
TABLE: studentsubject
FIELDS: student, subject, section, course, level
Thanks IN advance for the Help..

Answer 1

TRY
mysql_query("SELECT * FROM tbl_cur_sub where status=1 ");

Answer 2

change the mysql statement...you need to differ the variable and string in the query
$result = mysql_query("SELECT * FROM student WHERE id='".$id."'");