Checkbox group add to database - php

Question

I have the following query that retrieves client data to create a checkbox group. I need to add the selected checkboxes to a database as individual rows, but I am not sure how to write this as I have not done it before. I'm confused because the number of checkboxes will vary in number.
res=mysql_query('SELECT id,name FROM tbl_client WHERE active="1" ORDER BY name DESC',$dbh) or die(mysql_error());
num=mysql_num_rows($res);
for($run=0; $run<$num; $run++)
{
val=mysql_fetch_row($res);
echo '<label><input type="checkbox" name="CheckboxGroup1" value="'.$val[0].'" id="CheckboxGroup1_0" />'.$val[1].'</label><br />';
}
How do I access the checkboxes in order to add them to individual rows in a database when I submit them? I guess I could use some kind of Foreach statement, I just have no idea how to do it.

Answer 1

What you need is to use an array, which means naming your input fields with trailing opening [ and closing square brackets ] like so...
<label><input type="checkbox" name="CheckboxGroup[]" /></label><br />
What this does is create an array named CheckboxGroup in your $_POST or $_GET super globals (depending on which method the form uses), when the form is submitted to your PHP script. So if you had 1 or 1000 of these input elements in your HTML they will all populate under $_POST['CheckboxGroup'] -- or $_GET -- in PHP and you can iterate over them like this...
foreach ($_POST['CheckboxGroup'] as $checkbox) {
/* do whatever you want with $checkbox here */
}
Please note that a checkbox value is only sent in the request by the UA if it is checked. Also please don't use mysql_* functions to interface with your mysql database in PHP as it is deprecated and will be removed from future versions of PHP. For new applications please consider using either MySQLi or PDO to interface with your mysql database in PHP.

Answer 2

In HTML forms, the checkbox and radio controls are unique in that they are not present in the request if they are not fired by the client. So your script has to know in advance what checkboxes to expect. With inputs of type=text, submit, etc., the request contains the named control, even if the data string is empty.
There are several ways to accomplish this sort of thing. You can make arrays of checkboxes, with or without named elements, like this:'
<input type="checkbox" name="color[orange]" />Orange
<input type="checkbox" name="color[green]" />Green
You can also provide type=hidden form elements with the same names as the checkbox elements. The last form element of the same name is the one that will be presented with the request. By doing this you can always have a predictable number of elements. The hidden value will be in the request if the checkbox is not fired. The checkbox value will be there if the client selected the checkbox.
Try setting up a form that submits your checkbox tests to a PHP script that says this (shown here in its entirety)
<?php var_dump($_POST);