시소당
Select ename
From emp
Where emp_cat = (select max(category) from emp_categories)
And sal_range = (select max(sal_range) from emp_categories)
And empdept = 2000;
<개선안>
Select ename
From emp
Where (emp_cat, sal_range) = (select max(category), max(sal_range) from emp_categories)
And empdept = 2000;