单项选择题
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,并在每一组中取Number3的平均值。
A、SELECT AVG(Number3) FROM Students
B、SELECT AVG(Number3) FROM Students ORDER BY Number2
C、SELECT AVG(Number3) FROM Students GROUP BY Number2
D、SELECT AVG(Number3) FROM Students GROUP BY Number2,Number3