Funny friday Oracle SQL quiz: query running N seconds

Write a pure SQL query with PL/SQL that stop after :N seconds, where :N is a bind variable.

with v(start_hsecs, delta, flag) as (
  select
    hsecs as start_hsecs, 0 as delta, 1 as flag
  from v$timer
  union all
  select
    v.start_hsecs,
    (t.hsecs-v.start_hsecs)/100 as delta,
    case when (t.hsecs-v.start_hsecs)/100 > :N /* seconds */ then v.flag*-1 else v.flag+1 end as flag
  from v, v$timer t
  where v.flag>0 and t.hsecs>=v.start_hsecs
)
select delta
from v
where 0>flag
/
--end

SQL> var N number
SQL> exec :N := 3 /* seconds */;

PL/SQL procedure successfully completed.

SQL> select...

     DELTA
----------
      3.01

1 row selected.

Elapsed: 00:00:03.01

Another my solution using sys.standard.current_timestamp, so some internal pl/sql…:

select count(*) from dual 
connect by sys.standard.current_timestamp - current_timestamp <= interval'3'second;