[firebird-support] What is more effective execute block or select?

[hamacker sirhamac...@gmail.com [firebird-support]]

I would know whats methods is more effective, per exemple:
To know if itens exists or not, select:
select
  case
    when exists(select 1 from cv_itens  where id_cv=51716)
    then 'Y'
    else 'N'
  end as existe_itens
from rdb$database

OR using block execute:
execute block
returns(exist varchar(1))
as
begin
  exist='N';
  if (exists(select 1 from cv_itens  where id_cv=51716)) then exist='Y';
  suspend;
end

I think that first method using rdb$database as source, checking
permissions and others things and second method is not and more powerfull
using psql.

I would like to know what you guys think about.