Question

I’m creating a website and part of the functionality is that a user can create a list. Each user can only have one list, and each list only has one user. Each list also has a bunch of items. Items can be used in multiple lists.

So let’s say I have the following tables:

• Users
• Lists
• Items

How can I define which items a list has? Right now I’m storing a string of CSV’s in the Lists table, but I doubt that’s the best way.

Thanks!

Answer 1

Typically you would have table definitions like:

create table user (
  id int,
  name varchar,
  list_id int, /* optional */
  etc.
)

create table list (
  id int,
  name varchar,
  owner_id int
  etc.
)

create table item (
  id int,
  name varchar,
  etc.
)

create table item_x_list (
  id int,
  list_id int,
  item_id int
)

such that:

user -> list -> item_x_list -> item*

Note that you could skip the list table altogether if you didn’t need list-specific data like a name.