Updating when a checkbox is ticked

I have a form that extracts data from a mysql database and if a checkbox called update is checked it updates the database.

The problem is that if the update field is a checkbox the script updates the first record set regardless of whether the checkbox is checked or not and does not update the last record.

If I use a select menu instead of a checkbox it works fine.

Heres the relevant bits of the code:
<input name="update[]" type="checkbox" id="update" value="1">

for($i=0;$i<$count;$i++){
if($update[$i] ==1){

// do stuff ###DOES NOT WORK

*********************************************

<select name="update[]" id="update">
<option value="0" selected>No</option>
<option value="1">Yes</option>
</select>


for($i=0;$i<$count;$i++){
if($update[$i] ==1){

// do stuff ###WORKS FINE

Any ideas?

Thanks

 

your code seems to be fine.

 

is this a checkbox or a dropdown?
js or ajax?

use onchange event or onSelect on every checkbox that has the same name,
remeber to put a parameter
onchange="yourFunction(this.value)"

then catch it with $_REQUEST['checkboxname'];
then do your query here

 

The form is output by php as a standard html form.

When the update field is a checkbox it does not work but when it's a select it works fine.

PHP seems to be handling checkbox arrays differently than the text field arrays or the select box arrays.