Making a checkbox recognize its intended data - php

Question

Level: PHP Learner
I'm stuck with a checkbox problem. I have a db that contains names and unique id numbers.
Using a query, I am pulling a selection of students and showing them to a user in an ultra simple HTML table on a form. Each row begins with a checkbox. The method is POST. So far, so good. My table looks like this:
+-----------+----------+----------+
| SELECT | NAME | ID |
+-----------+----------+----------+
| [] | John | 2233 |
+-----------+----------+----------+
| [] | Susie | 5577 |
+-----------+----------+----------+
[-SUBMIT-]
My problem is that I cannot seem to make the checkbox associate with each record's unique ID. Once the user has selected rows and clicked submit, the $_POST array remains empty.
None of my beginners books reference this specific issue. They go through the "regular" checkbox routines that don't involve interacting with rows from a db. I also could not find an issue on Stackoverflow that addresses this. Also tried Google: plenty of stuff on checkboxes, but I couldn't find any that helped me on this problem.

Answer 1

Just do something like this:
<input type="checkbox" name="ids[]" value="2233" /> ... rest of row
<input type="checkbox" name="ids[]" value="5577" /> ... rest of row
Now, in PHP, you can get the selected ids like this:
$ids = $_POST['ids'];
if( empty($ids) ) $ids = array();
This sets $ids to an empty array if the form was submitted without any of the checkboxes checked.

Answer 2

Edit: If your form doesn't get more complex as you describe, take Doug Neiner's approach, as it is way simpler. This approach is right if a table is likely to have a number of columns.
I like to do it this way:
Number the checkboxes sequentially (1 to 100) and add a hidden field connecting the row number to a real database ID:
<input type="checkbox" name="row_1" value="checked">`
<input type='hidden' name='row_1_id' value='2233'>`
Store the total number of rows in another hidden field
<input type='hidden' name='row_total' value='99'>
Then, in the receiving script, iterate from 1 to the total number of rows using for, check whether this row was selected, and get the associated database ID:
for ($i = 1; $i <= $number_of_rows; $i++)
{
if ($_POST["row_$i"] == "checked")
{
$database_id_unsafe = $_POST["row_{$i}_id"];
...
the latter, of course, needs to be properly sanitized and escaped in case it is processed further.