Return null rows if not found in where mysql

Imagine have a request Like :

Select product_id,category, price  FROM mytable
WHERE category IN('fish', 'chips', 'nuggets')

But no products_id has a ‘chips’ category. Then it will return something like:

But I want display null for each conditions not found in where conditions:

How can I do that??

>Solution :

Use a calendar table approach along with a cross join:

SELECT p.product_id, c.category, t.price
FROM (SELECT DISTINCT category FROM mytable) c
CROSS JOIN (SELECT DISTINCT product_id FROM mytable) p
LEFT JOIN mytable t
    ON t.category = c.category AND
       t.product_id = p.product_id
WHERE c.category IN ('fish', 'chips', 'nuggets')
ORDER BY p.product_id, c.category;