select h.id, h.type, case h.type
	when 'PERSON' then p.firstname || ' ' || p.lastname 
	when 'COMPANY' then c.name
	when 'BANK' then b.name
end
from holder h
 left join person p on p.id = h.id 
 left join company c on c.id = h.id 
 left join bank b on b.id = h.id