Postgres 16

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create table orders(
	"user" text not null,
	mark text not null,
	mark_cnt bigint not null
);

insert into
	orders
values
	('U1', 'm1', 1),
	('U1', 'm2', 2),
	('U1', 'm3', 1),
	('U1', 'm4', 3),
    
	('U2', 'm1', 1),
	('U2', 'm2', 2),
	('U2', 'm4', 1),
	('U2', 'm6', 1),
    
	('U3', 'm1', 1),
	('U3', 'm2', 3),
	('U3', 'm3', 7),
	('U3', 'm4', 3),
	('U3', 'm5', 1),
    
	('U4', 'm1', 1),
	('U4', 'm2', 1),
	('U4', 'm4', 1);

CREATE TABLE



INSERT 0 16


select
    o1."user",
    o2."user"
from
    orders o1
left join
    orders o2
    on (
        o1."user" != o2."user" and
        o2.mark = o1.mark
    )
group by
    o1."user", o2."user"
having
    bool_and(
        coalesce(o2.mark_cnt, 0) >= o1.mark_cnt
    )


user
user


U4
U1

U4
U3

U2
U1

U2
U3

U4
U2

U1
U3



SELECT 6


select original."user", others."user"
from orders as original
join orders as others
  on others.mark = original.mark
 and others.mark_cnt >= original.mark_cnt
 and others."user" <> original."user"
group by
  original."user",
  others."user"
having
  count(*) = (select count(*) from orders as o where o."user" = original."user");


user
user


U4
U1

U4
U3

U4
U2

U1
U3



SELECT 4