PHP/HTML : How to access checkboxes dynamically generated in loop - php

Question

I have checkboxes which is generated in while loop. These checkboxes are always checked for the first time and the value stored in the database is "On". But when user unchecks it, I want to store "Off" in database. But my problem is i am not able to access the checkbox name to check if which checkboxes are unchecked on button click. I wrote this code
while($row = mysql_fetch_assoc($result)) {
if($pck_id_renew == 'On')
{
echo '<td class=c><input type="checkbox" id="renew_chk" name="renew_chk"
checked="checked" style="width:50px" value="On"/></td>';
}
if($pck_id_renew == 'Off') {
echo '<td class=c><input type="checkbox" id="renew_chk" name="renew_chk"
style="width:50px" value="Off"/></td>';
}
}

Answer 1

You will only receive the input value of checkboxes that are checked. Use an array and store all available checkbox names in it. Loop through this array to detect which checkboxes are checked/unchecked.
Code may look something like this:
// Define available checkboxes
$inputs = array('renew_chk', ...);
// Check input values
$values = array();
foreach ($inputs as $input) {
if (isset($_POST[$input])) {
$values[$input] = 'On';
}
else {
$values[$input] = 'Off';
}
}
// Loop through $values and store value in database
foreach ($values as $input => $value) {
// UPDATE database SET $input = $value WHERE id = [n];
}