Question

I have this 4 level user table as below

user_id parent_id
1       NULL
2       1
3       2
4       2
5       3
6       1

I would like to select all user under a certain parent id, for example, user_id = 1 and in this case shall return result like below:

user_id  parent_id
2        1         // return because parent_id = 1
6        1         // return because parent_id = 1
3        2         // return because parent_id of 2 is 1
4        2         // return because parent_id of 2 is 1
5        3         // return because parent_id of 3 is 2

By providing an id, what would be the query?

Thanks in advance!

Answer 1

Try this ::

    Select 
user_id 
from 

my_table 
where parent_id in 
(
Select 
user_id 
from my_table where parent_id in 
(Select user_id from my_table where parent_id in(Select user_id from my_table where parent_id =?)))