Wow, I can't fathom how this works. Where do you store the relationship, then? Say you have posts and comments. I would want a posts table and a comments table,

Wow, I can't fathom how this works. Where do you store the relationship, then? Say you have posts and comments. I would want a posts table and a comments table, with a post_id foreign key in comments. How would you do it without a foreign key?