---

Examine the description of the EMPLOYEES table: Which statement produces the number of different departments that have employees with last name Smith?（）
A:SELECT COUNT(*) FROM employees WHERE last_name='Smith';
B:SELECT COUNT(dept_id) FROM employees WHERE last_name='Smith';
C:SELECT DISTINCT(COUNT(dept_id)) FROM employees WHERE last_name='Smith';
D:SELECT COUNT(DISTINCT dept_id) FROM employees WHERE last_name='Smith';
E:SELECT UNIQUE(dept_id) FROM employees WHERE last_name='Smith';

---

出自：Oracle认证

显示答案