I’m not sure whether you think about:
select * from friend f
where not exists (
select 1 from likes l where f.id1 = l.id and f.id2 = l.id2
)
it works only if id1 is related with id1 and id2 with id2 not both.
I’m not sure whether you think about:
select * from friend f
where not exists (
select 1 from likes l where f.id1 = l.id and f.id2 = l.id2
)
it works only if id1 is related with id1 and id2 with id2 not both.