changing the value of a checkbox in the database

Question

I have a form with check boxes in it. I didn't set the value of the check boxes I always thought the value was either 'on' or '' (empty). I have the value 'on' passing to the database. The problem is when I unchecked the box it isn't changing the value in the database to '' (empty). The rest of the values of the form, such as input boxes are being changed. Here is my code on my check boxes

<input  type="checkbox" name="form3_one_2" <?php if($form3_one_2 == 'on'){print 'checked="checked"';}?> />

Am I supposed to have an value put into the form???

Answer 1

If you want to write it as selected on the browser, as it looks like you are, use

<input name="foo" selected="selected" ... />

If you want to get the result of the checkbox, it should indeed be "on" when you pass it via a form (or querystring, if you're using GET).

Answer 2

You should keep track of the checkbox(es) in the form. When the form is posted, do something like

<?php

if( 'POST' == $_SERVER[ 'REQUEST_METHOD' ] )
{
  /* for security reasons just check
   * if it isset and set it to 'on' yourself
   * never trust users input, always validate / sanitize
   */
  $form3_one_2 = isset( $_POST[ 'form3_one_2' ] ) ? 'on' : '' ;
}

?>

By the way: Where is your $form3_one_2 coming from anyway? I have a feeling you are still working with the ini setting register_globals on, which is also a huge security hole from the jurassic age. Be sure to program for register_globals set to off.