Aggreger efter medarbejder og brug string_agg
:
select
c.employee_id, -- or just c.* assuming employee_id is a PK
string_agg(ce.email, ',') as emails
from root.employee c
full outer join root.employee_email ce
on c.employee_id = ce.employee_id
group by
c.employee_id
order by
c.employee_id
limit 1000
offset 0;