Let user create table based on existing table - php

Question

After registering at my site, I want the user to select some elements from a table that already exists in my DB, and add them to "their" column in another table.
Say this is the existing table in a MySQL DB:
ID Item Color
1 Car Red
2 Apple Green
3 Trophy Gold
4 Suit Black
I would want the user to fill out a form where they:
Are presented with a dropdown list, to choose items from (based on the existing table).
When they have chosen up to x amount of items, they submit their "inventory" which..
Adds the selected items to their own column in a table that holds "user_inventory"
So this second table (user_inventory) should look something like this:
User_id item_id1 item_id2 item_id3
1 4 3 1
2 3 1 4
3 2 4 1
4 2 4 3
I don't expect you to write the code for me or anything, but I would be thrilled if you could answer these questions:
Is this possible?
Can you direct me to a similar type of thread or article that helps me write the code?
If you can not direct me anywhere, please help me in whichever way you see fit.

Answer 1

It is possible.
Firstly, read from the "existing" db table to create the select menu, example:
<select name="item">
<?php
$sql = "SELECT * FROM existing";
$query = mysqli_query($mysqli, $sql);
while ($result = mysqli_fetch_array($query)) {
$item = $result['item'];
echo "<option value='$item'>$item</option>";
}
?>
</select>
This will create the "Item" select menu, I'm sure you can figure out how to do the other menus by yourself, all that is left now is to submit and store into the new table which I assume you already know how to do.
if(isset($_POST['yoursubmitname'])) {
$item = $_POST['item'];
/// RUN THE INSERT COMMAND HERE //
}