功能介绍：
首先是进行无字段的聚合,然后在对字段进行从左到右依次组合后聚合
创建表：
Create Table score
(
classID Int,
studentName Varchar2(50),
subject varchar2(50),
score Int
);
插入测试数据：
Insert Into score values (001,'小徐','语文',87);
Insert Into score values (001,'小徐','数学',98);
Insert Into score values (001,'小徐','外语',99);
Insert Into score values (002,'小吴','语文',80);
Insert Into score values (002,'小吴','数学',74);
Insert Into score values (002,'小吴','外语',65);
Insert Into score values (003,'小张','语文',89);
Insert Into score values (003,'小张','数学',78);
Insert Into score values (003,'小张','外语',84);
Insert Into score values (004,'小孙','语文',100);
Insert Into score values (004,'小孙','数学',100);
Insert Into score values (004,'小孙','外语',100);
Insert Into score values (001,'小彭','语文',87);
Insert Into score values (001,'小彭','数学',99);
Insert Into score values (001,'小彭','外语',65);
Insert Into score values (004,'小叶','语文',100);
Insert Into score values (004,'小叶','数学',100);
Insert Into score values (004,'小叶','外语',100);
Insert Into score values (003,'小刘','语文',79);
Insert Into score values (003,'小刘','数学',90);
Insert Into score values (003,'小刘','外语',65);
Insert Into score values (002,'小童','语文',96);
Insert Into score values (002,'小童','数学',93);
Insert Into score values (002,'小童','外语',97);
普通分组函数，统计每个班级的总分：
Select t.Classid, Sum(t.Score) From Score t Group By t.Classid;
查询结果：
加上Rollup，统计每个班级的总分和所有班级的总分：
Select t.Classid, Sum(t.Score) From Score t Group By Rollup(t.Classid);
查询结果：
aaarticlea/png;base64,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" alt="" />
先进行无字段的聚合（1），再对Classid聚合（3），相当于：
Select Null, Sum(t.Score) From Score t
Union All
Select t.Classid, Sum(t.Score) From Score t Group By t.Classid;
在看看两个字段的，统计每个班级的总分、所有班级的总分和每个学生的总成绩：
Select t.classid,t.studentname,Sum(t.score) From Score t Group By Rollup(t.classid,t.studentname);
查询结果：
aaarticlea/png;base64,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" alt="" />
先进行无字段的聚合（1），再对Classid聚合（3），在对Classid和Studentname组合聚合，相当于：
Select Null, Null, Sum(t.Score) From Score t
Union All
Select t.Classid, Null, Sum(t.Score) From Score t Group By t.Classid
Union All
Select t.Classid, t.Studentname, Sum(t.Score) From Score t Group By t.Classid, t.Studentname