Identify if at least one row with given condition exists

Question

Employee table has ID and NAME columns. Names can be repeated. I want to find out if there is at least one row with name like \'kaushik%\'.

So query should return true/f

Answer 1

Commonly, you'd express this as either

SELECT COUNT(*)
  FROM employee
 WHERE name like 'kaushik%'
   AND rownum = 1

where the rownum = 1 predicate allows Oracle to stop looking as soon as it finds the first matching row or

SELECT 1
  FROM dual
 WHERE EXISTS( SELECT 1
                 FROM employee
                WHERE name like 'kaushik%' )

where the EXISTS clause allows Oracle to stop looking as soon as it finds the first matching row.

The first approach is a bit more compact but, to my eye, the second approach is a bit more clear since you really are looking to determine whether a particular row exists rather than trying to count something. But the first approach is pretty easy to understand as well.