1327 Undeclared variable: MAX_DISPLAY_ALSO_PURCHASED
in:
[select p.products_id, p.products_image from orders_products opa, orders_products opb, orders o, products p where opa.products_id = '1573' and opa.orders_id = opb.orders_id and opb.products_id != '1573' and opb.products_id = p.products_id and opb.orders_id = o.orders_id and p.products_status = 1 group by p.products_id order by o.date_purchased desc limit MAX_DISPLAY_ALSO_PURCHASED]