How to make a selection with multiple values ​​in one cell?

Question

MySQL

There is a list of goods with certain IDs and there is a list of stores with their own IDs. Each store can have several products, for example, a store with ID 1 has products ID - 1,2,3,4. How can you make a selection of products if you select products that have several id values ​​​​of the store to which they belong. Because to make a separate table with the content - product 1 - store 2, product 1 - store 3, product 2 - store 4 - this is a huge amount of data if there are 40 such products, and 100 stores are acceptable, and for each such product and for each store you need make your request to understand if there is a connection between them or not.

Answer 1

First of all, I advise you to learn Russian, since such a stream of consciousness is very difficult to read.
On business. I propose to consider for a start a simple implementation from opencrart'a.
product table:
- id
- name
- ...
store table:
- id
- name
- ...
product_to_store table:
- product_id
- store_id
Query to fetch all product data with the names of stores that have them:

SELECT 
    product.*,
    GROUP_CONCAT(store.`name`) AS 'stores'
FROM 
    `product` 
    JOIN `product_to_store` ON product_to_store.`product_id`=product.`id`
    JOIN `store` ON store.`id`=product_to_store.`store_id`