设students表有三列number1、number2、number3,并且都是整数类型,则以下()查询语句能按照number2列进行分组,并在每一组取number3的平均值。
A.
select avg(number3) from students
B.
select avg(number3) from students order by number1
C.
select avg(number3) from students group by number2
D.
select avg(number3) from students group by number3,number2