Question

How to select clients who signed contracts with all subsidiaries?

R2
    UID | Subsidiary
    1   | 1
    1   | 2
    1   | 3
    2   | 1
    2   | 2
    3   | 1
    3   | 1

Could you help me with this question?

Answer 1

Something like this:

select u_r2.uid
from 
     (select uid
           , count(distinct subsidiary) as u_subs
     from r2
     group by uid )  u_r2
  , 
    (select count (distinct subsidiary) as tot_subs
     from r2) sub_r2
where sub_r2.tot_subs = u_r2.u_subs;