Oracle: Id Not in another table

I have following two tables, airport and flying

create table airport(airport_id number,flying_id,flying_company);

create table flying(flying_id,flying_company);

select airport_id 
from airport 
where flying_id not in(select flying_id from flying);

I would like to get airport_id where flying_id present in flying table but not present in airport table. I rote the following query using nested select query. Is there anyway I can improve without writing nested?

select airport_id 
from airport 
where flying_id not in (select flying_id from flying);

Answer

There are two ways.

• LEFT JOIN

    SELECT DISTINCT F.*
      FROM FLYING F 
    LEFT JOIN AIRPORT A
        ON F.FLYING_ID = A.FLYING_ID
    WHERE A.AIRPORT_ID IS NULL;

• NOT EXISTS

SELECT F.*
  FROM FLYING F
 WHERE NOT EXISTS 
       (SELECT 1 FROM AIRPORT A
         WHERE A.FLYING_ID = F.FLYING_ID);