Foreach Loop For NOT NULL

[rahaiffi]

I'm sure this is a pretty simple question, but it's got me baffled.

 $id = $_POST['id'];
$sem = $_POST['sem'];
$year = $_POST['year'];
if(is_array($_POST['mark']) and
   is_array($_POST['gred']) and
   is_array($_POST['code']) and
   is_array($_POST['subject']))
{
   $values = array();
   foreach($_POST['mark'] as $key => $mark)
   {
      $gred = $_POST['gred'][$key];
      $code = $_POST['code'][$key];
      $subject = $_POST['subject'][$key];
      $values[] = "('$id','$sem','$year','$mark','$gred','$code','$subject')";
   }
   $query = "INSERT INTO result ".
            "(id_stud, sem, year, mark, gred, subject_code, name_subject) ".
            "VALUES " . implode(",", $values);
   $result = mysql_query($query) or die("Query failed: $query - " . mysql_error());
} 

This foreach loop insert all the data even user do not input the mark and gred input..In the database value of gred and mark as NULL.
i want to insert all the data only when user input the mark and gred only..
Please help me..

[devinemke]

what does your form look like?

[rahaiffi]

This is my form:

<form name="form1" id="form1" method="post" action="page.php">
            <table width="91%"  border="0" cellspacing="0" cellpadding="0">
              <tr>
                <td width="16%"><div align="center">Code </div></td>
                <td width="50%"><div align="left">Subject</div></td>
                <td width="21%">MARK</td>
                <td width="13%">GRED</td>
              </tr>
              <?php do { ?>
              <tr>
                <td><div align="center"><?php echo $row_subject['CODE_SUBJ']; ?>
                  <input name="code[]" type="hidden" value="<?php echo $row_subject['CODE_SUBJ']; ?>" />
                </div></td>
                <td><div align="left"><?php echo $row_subject['NAME_SUBJECT']; ?>
                  <input name="subject[]" type="hidden" value="<?php echo $row_subject['NAME_SUBJECT']; ?>" />
                </div></td>
                <td><input name="mark[]" type="text" size="3" maxlength="3" />
                  %</td>
                <td><select name="gred[]">
				  <option selected value="">Select</option>
                  <option value="A">A</option>
                  <option value="B">B</option>
                  <option value="C">C</option>
                  <option value="D">D</option>
                  <option value="E">E</option>
                </select></td>
              </tr>
              <?php } while ($row_subject = mysql_fetch_assoc($subject)); ?>
              <tr>
                <td>&nbsp;</td>
                <td>&nbsp;</td>
                <td>&nbsp;</td>
                <td>&nbsp;</td>
              </tr>
              <tr>
                <td>&nbsp;</td>
                <td><input name="id" type="hidden" value="<? echo $_GET['idstudent'];?>" />
                  <input name="sem" type="hidden" value="<? echo $_GET['sem'];?>" />
                  <input name="year" type="hidden" value="<? echo $_GET['year'];?>" />
                        <input name="Send" type="submit" class="button" id="Send" value="Send" /></td>
                <td>&nbsp;</td>
                <td>&nbsp;</td>
              </tr>
            </table>
          </form>

[rahaiffi]

i try this coding..

$id = $_POST['id'];
$sem = $_POST['sem'];
$year = $_POST['year'];
if(is_array(!empty($_POST['mark'])) and
   is_array(!empty($_POST['gred'])) and
   is_array($_POST['code']) and
   is_array($_POST['subject']))
{
   $values = array();
   foreach($_POST['mark'] as $key => $mark)
   {
      $gred = $_POST['gred'][$key];
      $code = $_POST['code'][$key];
      $subject = $_POST['subject'][$key];
      $values[] = "('$id','$sem','$year','$mark','$gred','$code','$subject')";
   }
   $query = "INSERT INTO result ".
            "(id_stud, sem, year, mark, gred, subject_code, name_subject) ".
            "VALUES " . implode(",", $values);
   $result = mysql_query($query) or die("Query failed: $query - " . mysql_error());
} 

there is no error but..
the data doesn't insert in the database..