Andrew, I made a few adjustments to your script, this should do what you
want.  It appears that you had a mixup in your selected subjects query.
Although, this may be a little slow because it makes a query after every
subject to see if it is checked.

$full_result = mysql_query("SELECT supersub_id, supersubject FROM
supersubs ORDER BY supersubject");
while ($supersub = mysql_fetch_assoc($full_result)) {
    $faq_result = mysql_query("SELECT faq_id FROM faq_supersubs WHERE
supersub_id = '" . $supersub['supersub_id'] ."'");
    if (mysql_num_rows($faq_result)) {
        echo '<input type="checkbox" name="id" value="' .
$supersub['supersub_id']. '" CHECKED> ' . $supersub['supersubject'];
    } else {
        echo '<input type="checkbox" name="id" value="' .
$supersub['supersub_id']. '"> ' . $supersub['supersubject'];
    }
}

A much more efficient way would to do some sort of outer join in order
to get a field that acts as a switch for checking if the checkbox should
be checked or not.

Andrew Darby wrote:

> PHP people, I fall upon your mercy!  I'm trying to do something which
> shouldn't be so hard:  to allow a user to edit an existing entry to a
> FAQ database, I want to query the table of subjects to generate tick
> boxes for all subjects, and query the faq_subjects intervening table to
> determine which subjects are associated with that FAQ, and then combine
> them into one long list of checkboxes, with the already selected
> subjects CHECKED.
>
> So, after spending way too much time on it, I made it work using
> is_array to compare the two arrays of results, only to discover, when
> putting it on my live server, that is_array doesn't accept an array for
> the second value in MySQL versions < 4.2.
>
> So, can anyone suggest another way to do this?  The code using is_array
> is below.  Any help would be greatly appreciated; i'm going around in
> circles on this, and as a one man shop, i've got no one to bounce this
> off of [insert frowny face here].
>
> Thanks,
>
> Andrew
>
> p.s. if this sort of nuts and bolts question is inappropriate for this
> list, please let me know!
>
> ------- Used to Work PHP Code --------
>
> //selected_subjects_query determines which subjects should be pre-ticked.
>
> $selected_subjects_query = "SELECT faq.faq_id,
> faq_supersubs.supersubs_id FROM faq, faq_supersubs
> WHERE faq.faq_id = faq_supersubs.faq_id
> AND faq.faq_id = '$this_id'";
>
> // this will create an array of all items already checked
>
> $selected_subjects_result = MYSQL_QUERY($selected_subjects_query);
> $checked_ones = "";
> while($myrow =  mysql_fetch_array($selected_subjects_result)) {
> $checked_ones[] .= $myrow['1'];
> }
>
> $full_query = "SELECT supersub_id, supersubject FROM supersubs ORDER BY
> supersubject";
>
> /* Select all active records (this is based on a db connection made
> above)*/
>
> $full_result = MYSQL_QUERY($full_query);
>
> // create the checkboxes
>
> while($myrow =  mysql_fetch_array($full_result))
> {
>        $sub_id = $myrow["0"];
>        $sub_name = $myrow["1"];
>
> if (!in_array($sub_id, $checked_ones)) {
>
>        $checkboxes .= "<input name=\"subject[]\" type=\"checkbox\"
> value=\"$sub_id\">$sub_name</input><br />";
>
> } else {
>
>        $checkboxes .= "<input name=\"subject[]\" type=\"checkbox\"
> value=\"$sub_id\" CHECKED>$sub_name</input><br />";
>
> }
>
> }