PHP - Imitate How the "Map Network Drive" Dropdown Works - php

Question

I'm trying to imitate how the Windows "Map Network Drive" dropdown works. My dropdown options are the letters A-Z. Based on the results from my SQL SELECT statement, I need to show but disable those letters that are already in use. I'm able to get the letters in the dropdown, or get my SQL results in the dropdown but not the correct combination of both.
How do I display all letters of the alphabet in a dropdown and disable those that come back in my SQSL SELECT statement?
Example DB
ID | Desc
-----------
A | Desc A
D | Desc D
F | Desc F
J | Desc J
Z | Desc Z
So for example, using the example DB above, the letters 'A, D, F, J, Z' would be displayed but disabled whereas all other letters in the alphabet would be selectable.
This is the code I currently have. It's very close to being correct but somehow out of order. It does display every letter of the alphabet and my database results (with those results disabled) BUT every letter of the alphabet is displayed for every database result. Again using the Example DB above, the code below would display the letters 'A' through 'Z' for each result (5 times) and each time disable that result only.
<select>
<?php
// SQL select from Example DB table and connection
while ($row = odbc_fetch_array($db)) {
foreach (range('A', 'Z') as $value) {
if ($row['id'] == $value) {
$result = $value.' -- '.$row['desc'];
$dis = "disabled";
} else {
$result = $value;
$dis = "";
}
?>
<option <?php echo $dis; ?>><?php echo $result; ?></option>
<?php
}
}
?>
</select>
I've tried moving the 'while' and 'foreach' around but haven't seemed to get them in the correct order.

Answer 1

You need to first query your database for letters in use, and then create a looping statement that goes from A to Z, and either marks the <option> as disabled or not.
<?php
$inUse = array();
$sql = "SELECT UNIQUE(`ID`) FROM `table` ORDER BY `ID` ASC";
$res = $db->query($sql);
foreach ($drive as $res->fetchObject()) {
$inUse[] = $drive['ID'];
}
// create select list
echo '<select name="drive">';
foreach (range('A', 'Z') as $letter) {
$disabled = (in_array($letter, $inUse)) ? ' disabled="disabled"' : '';
echo '<option value="' . $letter . '"' . $disabled . '>' . $letter . '</option>';
}
echo '</select>';

Answer 2

Untested, but you could try this:
<select>
<?php
$range = range('A', 'Z');
$used = array();
// Fill in used drives along with their descriptions
while ($row = odbc_fetch_array($db)) {
$used[$row['ID']] = $row['desc']);
}
foreach ($range as $value) {
$result = $value;
$dis = "";
if (in_array($value, $used) {
$result .= ' -- '.$used[$value];
$dis = 'disabled="disabled"';
}
?>
<option <?php echo $dis; ?>><?php echo $result; ?></option>
<?php
}
?>
</select>