If I'm reading this right, you want a many-to-many relationship between
Products and Jobsites. To do this, you'll want a simple 'join' table
which holds an entry for each product used at each site.
This table has a one-to-many relationship with each of the other
For your gold lamp query, do
FROM josites j
INNER JOIN products_jobsites p_j
ON j.id = p_j.jobsite_id
INNER JOIN products p
ON p_j.product_id = p.id
WHERE p.name like 'Gold Lamp';
That what you need?