What's the most efficient way to check if a record exists in Oracle?

Question

A)

select decode(count(*), 0, 'N', 'Y') rec_exists from (select 'X'       from dual       where exists (select 'X'                     from sales                     where sales_type = 'Accessories')); 

B)

select decode(count(*), 0, 'N', 'Y') rec_exists from (select 'X'       from sales       where sales_type = 'Accessories');  

C) Something else (specify)

EDIT: It was hard to pick the "correct" answer, as the best approach depends on what you want to do after checking if the value exists, as pointed out by APC. I ended up picking the answer by RedFilter, since I had originally envisioned this check as a function by itself.

Answer 1

select case              when exists (select 1                           from sales                           where sales_type = 'Accessories')              then 'Y'              else 'N'          end as rec_exists from dual;