populating a checkbox from database

[eluser]sore eyes[/eluser]
Many thanks for this Obiron, it was just what I wanted. I'm still struggling a bit, as this is my first join. I have made some modifications. The query now reads

Code:

$query = $this->db->query("SELECT products.product_id,count(productsbyshop.product_id)
AS counting FROM products LEFT JOIN productsbyshop ON
products.product_id = productsbyshop.product_id
WHERE productsbyshop.shop_id = '$shop_id'
GROUP BY products.product_id ORDER by products.product_id");

The problem is that it does not list all the products, only those that are selected. I thought that having the table 'products' on the left of the 'left join' would make it show all of the products, but it does not. I did not understand what the single 'p' and 's' were in the query, so I removed them and this may be the source of the error.

Can you help please?