How to margin after join?

Question

SQL

after this script,

select o.email, u.email from apartments a
left join users u on u.id = a.publisher_id AND a.publisher_type=0
left join organizations o on o.id=a.publisher_id AND a.publisher_type=1

outputs like this

email                   |    email
[email protected] | NULL
NULL                   | [email protected]

how can i make it output

email 
[email protected]
[email protected]

Answer 1

Select coalesce(o.email, u.email)...

Answer 2

Another option:

select email from users where id in(
  select distinct publisher_id from apartments where publisher_type=0
)
UNION 
select email from organizations where id in(
  select distinct publisher_id from apartments where publisher_type=1
)