Originally Posted by DjDanHayden
the changed ones, from 0 to 1 (checked) or else from 1 to 0 (unchecked)
Ah I think I see what you mean now!
What I think you mean is that you want them set to one if they are checked and otherwise set to 0.
The problem is that checkboxes are only sent by the browser to php if they are checked so there is no way so submit an empty check box.
You have two options:
1) Update all the fields to 0 and then update the selected ones to 1 afterwards (2 queries but possibly better than the next idea)
2) Change the form input to something else like radio buttons that will submit both true and false selections and then run either a large query if you can or multiple queries in a loop.
There is no way to know in php that a check box is not checked unless you store them / their id in a session before printing out the page and then compare what is submitted back from that form against this list.