I'm working on an iOS shopping application. And I use python to write my backend.

As for the cart part, I want to store a bunch of product ids in a `list` object.

By the way, I use `SQLAlchemy` to process sql queries.

As I don't have much experience in database design, I wonder what is the best way to store a `list` object into mysql.

I think this is a one-many relationship issue and I'm wondering **whether I need a third table** except for a `CartItem` table to store products' ids and a `Product` table to store product's id?

Someone said that `serialization` is a choice. What is `serialization`?

Or can I just split list elements by comma and store as a `string`?

I've referred some question answers like

[Store list of values (such as interests)](https://stackoverflow.com/questions/7766322/store-list-of-values-such-as-interests)

[store list of IDs mysql](https://stackoverflow.com/questions/8748610/store-list-of-ids-mysql)

[How to store a dynamic List into MySQL column efficiently?](https://stackoverflow.com/questions/1917106/how-to-store-a-dynamic-list-into-mysql-column-efficiently)