Re: Operand should contain 1 column(s) - how to get extra info from subquery?

[Peter Brawley]

Is this what you mean?

select p.person_last, p.person_first, ifnull(t.persontag_enddate,'Unknown') as 'expiry date'
from persons p
left join persons_tags t using(person_id)
where t.persontag_enddate is null or t.persontag_enddate > now()-interval 3 year
order by person_last, person_first;