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 NVL ((select 'Y' from  dual where exists
   (select  1 from sales where sales_type = 'Accessories')),'N') as rec_exists
from dual

1.Dual table will return 'Y' if record exists in sales_type table 2.Dual table will return null if no record exists in sales_type table and NVL will convert that to 'N'