Question

I have two database tables with a one-to-many relationship. Is it possible to select records from the ‘one’ table for which no records exist in the ‘many’ table using a single SQL statement? If so, how?

Thanks in anticipation.

Answer 1

Use an OUTER JOIN:

select p.id
from parent p
left outer join child c on c.parent_id = p.id
where c.parent_id is null