Question

I am working on a project which user registration multiples like this.
1st Month -> 1 user
2nd Month -> 4 users comes under the above user
3rd Month -> 16 users (i.e, 4 users comes under each 4 users above )
4th Month -> 64 users (i.e, 4 users comes under each 16 users above )

eg:
1
    2 | 2
    8 | 8
   32| 32

and continues…

Please give me an advice, how to store this in database.
Thanks in advance.

Answer 1

Assuming user_id is your primary key, create a parent column that contains the user_id of the parent user. For example:

user_id  parent
1        NULL
2        1
3        1
4        1
5        1
6        2
...

You will also want to create an index on the parent column so that you can quickly do a reverse lookup (i.e. find all children of a given user).