Oracle date difference with case

I have the followin开发者_开发知识库g:

 select nvl ( 
     (select 1
      from tableA, tableB 
      where tableA.id(+) = 9999
      and tableB.project_id(+) = tableA.project_id
      and sysdate - tableA.start_date < 120), 0) as myFlag from dual;

I am trying to see if the project start date is less than 120 or not. The above query works but is there a better way of doing this? Like with a case statement?

---

select 
  case 
      when sysdate-tableA.start_date < 120 then 1
      else 0
  end myFlag
from tableA, tableB 
where tableA.id(+) = 9999
and tableB.project_id(+) = tableA.project_id

---

Why are you left joining to table B? Couldn't you just do this?

SELECT CASE WHEN ID IS NULL THEN 0 ELSE 1 END
FROM TableA 
WHERE sysdate - TableA.start_date < 120 and TableA.id = 9999;