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
           


        

Answer 1

SELECT 'Y' REC_EXISTS             
FROM SALES                       
WHERE SALES_TYPE = 'Accessories'

The result will either be 'Y' or NULL. Simply test against 'Y'