Question

I’m creating a tree view for a website using databases. I will create 2 tables, let’s call them “Folder” and “File”. A folder can contain multiple folders and files, and files will act as leaf nodes – which means they’re a “dead end” in the tree if you’re unfamiliar with the term.

The folder table will contain columns:

Folder_id, Folder_name, Folder_parent

File will contain:

File_id, File_name, File_parent

Obviously File_parent will reference a folder_id, thus creating a foreign key, but how do I make the Folder_parent reference the Folder_id?

Example:

FOLDER_NAME   | FOLDER_ID   | FOLDER_PARENT
root               1               null 
Cars               2                 1 
Planes             3                 1 
BMW                4                 2 

Answer 1

create table folder (
  folder_id int primary key,
  folder_name varchar not null,
  folder_parent int references folder(folder_id)
)