Update MySQL DB with PHP from Checkbox - php

Question

I am pulling data down from a MySQL table and loading it into a form for editing(updating) a record. Everything is working great until I come the the check boxes. The checkboxes in the form accurately reflect the values in the appropriate columns in the db. But when the person editing changes the checkbox in the edit form it does not pass the data to the database. I have read a ton of checkbox Q&A on stack overflow but don't seem to find what I am looking for. Sorry if this is a redundant Question. Here is the code.
<label for="amenities-beach">
<input class="choose" name="amenitiesB" id="amenities-beach" type="checkbox"
value="<?php echo $row1["amenitiesB"]; ?>"
<?php echo $row1["amenitiesB"] ? 'checked="checked"' : ''; ?> />
Close to Beach</label>
Where amenitiesB in:
value="<?php echo $row1["amenitiesB"]; ?>
is what has been returned from the DB with a SELECT statement with:
$row1 = mysql_fetch_array($result);
But when I change the value in the form and submit it nothing is passed to the variable in the UPDATE statement. Any idea what I am missing? I have 6 of these checkboxes,amenitiesB, amenitiesK, amenitiesS, amenitiesP, amenitiesF, and preferred all with the same code. Any help would be appreciated.
Thank You,
Dave
Ok here is the code: Everything else in the form updates fine. I attempt to pass it to:
$amenitiesB = $_POST['amenitiesB'];
then I put it into the update statement
Hotels.amenitiesB='".$amenitiesB."',
My UPDATE statement is,
$query="UPDATE Hotels
JOIN surfcup_Rates ON Hotels.id = surfcup_Rates.hotelid
SET Hotels.hotel='".$hotel."',
More columns, then
Hotels.amenitiesB='".$amenitiesB."',
Hotels.amenitiesB='".$amenitiesK."',
Hotels.amenitiesB='".$amenitiesS."',
Hotels.amenitiesB='".$amenitiesP."',
Hotels.amenitiesB='".$amenitiesF."',
Hotels.amenitiesB='".$preferred."',
More columns then:
WHERE Hotels.id='".$id."'";

Answer 1

The problem you have comes because when a checkbox is unchecked, by default its data is not transmitted to your PHP, and that's why you have problems by having the UPDATE query parameter empty.
So before your update statement you should have:
$fieldenabled=(bool)(isset($_POST['CHECKBOXNAME']) ? TRUE : FALSE;
And call your UPDATE query with that.
EDIT: Of course you can change $_POST with $_GET depending on the sending method of the <form>

Answer 2

Edit: I think I get the problem. When the box is initially unchecked, the input has an empty value, then when you check it, it passes an empty value in... it will never fill with what you intend the checked value to be. So, instead you need something like this:
<input class="choose" name="amenitiesB" id="amenities-beach" type="checkbox" value="amenity B Selected" <?php echo $row1["amenitiesB"] ? 'checked="checked"' : ''; ?> />
... don't make the "value" attribute dynamic, or else once it becomes empty it will always be empty.
Original Answer:
I assume when you say "change the value in the form" you mean that you uncheck the checkbox... unchecked checkboxes never send any data when you submit the form. You check for "unchecked" status by checking to see if the form variable has been passed at all.
For example:
if (isset($_GET['amenitiesB'])) {
// process with the knowledge that "amenitiesB" was checked
}
else {
// process with the knowledge that "amenitiesB" was unchecked
}
If you mean that you somehow dynamically change the "value" of the checkbox to something else, then I'll need to see the code that accomplishes that.
The main purpose of the "value" attribute in a checkbox input is when you're passing the variable as an array:
<label for="amenities-beach">
<input class="choose" name="amenities[]" id="amenities-beach" type="checkbox" value="<?php echo $row1["amenitiesB"]; ?>" <?php echo $row1["amenitiesB"] ? 'checked="checked"' : ''; ?> />
Close to Beach
</label>
... note specifically that I've changed the "name" attribute from "amenitiesB" to "amenities[]", which, if carried through all of your amenities checkboxes, will give you access to them all in your processing script through the $_GET['amenities'] array (or $_POST, if applicable). Otherwise, there's not much reason to use the "value" attribute of the checkbox input, because you can get all you need just by knowing $_GET['amenitiesB'] is checked (and thus sent with the form) or unchecked (and not sent with the form).