다음 중 연관(Correlated) 서브쿼리에 해당하는 것은?

1. 1SELECT * FROM emp WHERE sal > (SELECT AVG(sal) FROM emp)
2. 2SELECT * FROM emp e WHERE sal > (SELECT AVG(sal) FROM emp WHERE deptno = e.deptno)
3. 3SELECT * FROM emp WHERE deptno IN (SELECT deptno FROM dept WHERE loc = 'SEOUL')
4. 4SELECT * FROM emp WHERE EXISTS (SELECT 1 FROM dual)