OCP 071 每日一題

Choose the best answer.
Examine the description of the EMPLOYEES table:
Name Null Type

EMP_ID NOT NUL NUMBER
EMP_NAME VARCHAR2 (40)
DEPT_ID NUMBER(2)
SALARY NUMBER(8,2)
JOIN_DATE DATE
Which query is valid?
A) SELECT dept_id, join_date,SUM(salary) FROM employees GROUP BY dept_id, join_date;
B) SELECT depe_id,join_date,SUM(salary) FROM employees GROUP BY dept_id:
C) SELECT dept_id,MAX(AVG(salary)) FROM employees GROUP BY dept_id;
D) SELECT dept_id,AVG(MAX(salary)) FROM employees GROUP BY dapt_id;
Answer: A