Case com SubSelect

select uo.object_name, uo.object_type, case object_type   when 'TABLE' then (select comments from user_tab_comments tb where tb.table_name = uo.object_name)   when 'INDEX' then (select 'PK da tabela ' || table_name from user_constraints uc where uc.CONSTRAINT_NAME = uo.object_name) end from user_objects uo order by uo.object_type, uo.object_name