在SQL的查询语句中，GROUP BY选项实现（）功能。

A.GROUP BY

B.DISTINCT

C.ORDER BY

D.WHERE

A.CASCADE

B.PRIMARY KEY

C.CHECK

D.FOREIGN KEY和REFERENCES

A.如果未指定排序字段，则默认按递增排序

B.数据表的字段都可用于排序

C.如果未指定DESC或ASC关键字，则默认按递增排序

D.ORDER BY子句不能按多个排序表达式进行排序

A.CNo ='2001190101' AND CNo ='2001190102'

B.CNo!='2001190101' AND CNo!='2001190102'

C.CNo <>'2001190101' OR CNo!='2001190102'

D.CNo!='2001190101' OR CNo # '2001190102'

A.UPDATE

B.DELETE

C.TRUNCATE

D.ALTER

A.WHERE

B.HAVING

C.GROUP BY

D.FROM

A.WHERE

B.HAVING

C.ORDER BY

D.FROM

A.数据查询

B.数据更新

C.数据定义

D.数据控制

A.DELETE FROM grade;

B.DROP TABLE grade;

C.DELETE grade;

D.ALTER TABLE grade DROP grade;