Retrieve data from query filled drop down box - php

Question

I have made a dropdown box that is filled by a query that looks for company names from company name database, these names also have and ID number that I don't want displayed but are looked up in the query. I need the ID number to link to sites of the company so somehow when I hit the submit button on the site page it finds the ID number by looking at the position value and relating that to the position on the query array I just don't know what to do. If it helps this is how I fill the dropbox:
mysql_select_db("DB", $con);
$query = "SELECT Company_Name, ID FROM company_table";
$result = mysql_query($query) or die(mysql_error());
$options ='';
$num = 0;
while ($row=mysql_fetch_array($result)) {
$num = $num+1;
$options.= "<OPTION VALUE=\"$num\">".$row["Company_Name"];
}
<SELECT NAME=thing>
<OPTION VALUE=0>Choose
<?=$options?>
</SELECT>
Any Ideas?

Answer 1

There are two immediate ways this can be done. One is to keep it the way you have it using an index, $num; the other way is to use the actual company id field, ID. If you stick with the index of $num, when the user submits the form (i.e. - selects a company), you will have to re-query the database and re-loop through the results to find the specific company (or you could use a LIMIT/OFFSET; notes at end of answer).
I would recommend using the actual company id in your form:
while (($row = mysql_fetch_assoc($result))) {
$options.= '<option value="' . $row['ID'] . '">' . $row["Company_Name"] . '</option>';
}
This will generate a list of options, like you currently have, except the value of each will be the specific company id. When the user submits the form, let's assume the form is using POST, you can get the ID with:
$companyId = (isset($_POST['thing']) && is_numeric($_POST['thing'])) ? intval($_POST['thing']) : false;
$results = mysql_query('SELECT * FROM company_table WHERE ID=' . $companyId);
.. and then process as you desire.
I use $_POST['thing'] in the above example as that is what your code-example has the select field named. Also, I make the assumption that ID is an integer.
If the actual ID needs to remain hidden, as specified, the index of $num can be used with MySQL's LIMIT/OFFSET as follows:
$selectedCompany = (isset($_POST['thing']) && is_numeric($_POST['thing'])) ? intval($_POST['thing']) : -1;
if ($selectedCompany >= 0) {
$query = "SELECT Company_Name, ID FROM company_table LIMIT " . $selectedCompany . ", 1";
// process as desired
}

Answer 2

An option is to add a "created" field to the company table that is a timestamp, or just a 2nd column that is a random UUID column. Then set the value of the dropdown to this column so you don't show ID but you will still know the record since you are using the "other" id as well.
I actually use this method in one of my programs where it was the same situation as you, the client didn't want the ID to be shown.
If you don't want to go with this method (because you don't want a 2nd column) you could just md5 hash the ID or some other hashing method.
Then you would do
SELECT * FROM company where md5(id) = "$value".
The downside to this method is that it is an expensive query, since you won't be using an index and it has to compute all the md5 hashes for each id.