oracle分组函数之ROLLUP

 

1.初始化实验坏境

1）创建测试表group_test

sec@ora10g> create table group_test (group_id int, job varchar2(10), name varchar2(10), salary int);

Table created.

2）初始化数据

insert into group_test values (10,'Coding',    'Bruce',1000);

insert into group_test values (10,'Programmer','Clair',1000);

insert into group_test values (10,'Architect', 'Gideon',1000);

insert into group_test values (10,'Director',  'Hill',1000);

insert into group_test values (20,'Coding',    'Jason',2000);

insert into group_test values (20,'Programmer','Joey',2000);

insert into group_test values (20,'Architect', 'Martin',2000);

insert into group_test values (20,'Director',  'Michael',2000);

insert into group_test values (30,'Coding',    'Rebecca',3000);

insert into group_test values (30,'Programmer','Rex',3000);

insert into group_test values (30,'Architect', 'Richard',3000);

insert into group_test values (30,'Director',  'Sabrina',3000);

insert into group_test values (40,'Coding',    'Samuel',4000);

insert into group_test values (40,'Programmer','Susy',4000);

insert into group_test values (40,'Architect', 'Tina',4000);

insert into group_test values (40,'Director',  'Wendy',4000);

commit;

3）初始化之后的数据情况如下：

sec@ora10g> select * from group_test;

GROUP_ID JOB        NAME           SALARY

---------- ---------- ---------- ----------

10 Coding     Bruce            1000

10 Programmer Clair            1000

10 Architect  Gideon           1000

10 Director   Hill             1000

20 Coding     Jason            2000

20 Programmer Joey             2000

20 Architect  Martin           2000

20 Director   Michael          2000

30 Coding     Rebecca          3000

30 Programmer Rex              3000

30 Architect  Richard          3000

30 Director   Sabrina          3000

40 Coding     Samuel           4000

40 Programmer Susy             4000

40 Architect  Tina             4000

40 Director   Wendy            4000

16 rows selected.

2.先看一下普通分组的效果：对group_id进行普通的group by操作---按照小组进行分组

sec@ora10g> select group_id,sum(salary) from group_test group by group_id;

GROUP_ID SUM(SALARY)

---------- -----------

30       12000

20        8000

40       16000

10        4000

3.对group_id进行普通的roolup操作---按照小组进行分组，同时求总计

sec@ora10g> select group_id,sum(salary) from group_test group by rollup(group_id);

GROUP_ID SUM(SALARY)

---------- -----------

10        4000

20        8000

30       12000

40       16000

40000

翻译一下上面的SQL语句如下（union all一个统计所有数据的行）：

sec@ora10g> select group_id,sum(salary) from group_test group by group_id

2  union all

3  select null, sum(salary) from group_test

4  order by 1;

GROUP_ID SUM(SALARY)

---------- -----------

10        4000

20        8000

30       12000

40       16000

40000

4.再看一个rollup两列的情况

sec@ora10g> select group_id,job,sum(salary) from group_test group by rollup(group_id, job);

GROUP_ID JOB        SUM(SALARY)

---------- ---------- -----------

10 Coding            1000

10 Director          1000

10 Architect         1000

10 Programmer        1000

10                   4000

20 Coding            2000

20 Director          2000

20 Architect         2000

20 Programmer        2000

20                   8000

30 Coding            3000

30 Director          3000

30 Architect         3000

30 Programmer        3000

30                  12000

40 Coding            4000

40 Director          4000

40 Architect         4000

40 Programmer        4000

40                  16000

40000

21 rows selected.

上面的SQL语句该如何翻译呢？

如下：

sec@ora10g> select group_id,job,sum(salary) from group_test group by group_id, job

2  union all

3  select group_id,null,sum(salary) from group_test group by group_id

4  union all

5  select null,null,sum(salary) from group_test

6  order by 1,2;

GROUP_ID JOB        SUM(SALARY)

---------- ---------- -----------

10 Architect         1000

10 Coding            1000

10 Director          1000

10 Programmer        1000

10                   4000

20 Architect         2000

20 Coding            2000

20 Director          2000

20 Programmer        2000

20                   8000

30 Architect         3000

30 Coding            3000

30 Director          3000

30 Programmer        3000

30                  12000

40 Architect         4000

40 Coding            4000

40 Director          4000

40 Programmer        4000

40                  16000

40000

21 rows selected.

5.补充一步，尝试一下grouping

直接看效果就OK了：

sec@ora10g> select group_id,job,grouping(GROUP_ID),grouping(JOB),sum(salary) from group_test group by rollup(group_id, job);

GROUP_ID JOB        GROUPING(GROUP_ID) GROUPING(JOB) SUM(SALARY)

---------- ---------- ------------------ ------------- -----------

10 Coding                      0             0        1000

10 Director                    0             0        1000

10 Architect                   0             0        1000

10 Programmer                  0             0        1000

10                             0             1        4000

20 Coding                      0             0        2000

20 Director                    0             0        2000

20 Architect                   0             0        2000

20 Programmer                  0             0        2000

20                             0             1        8000

30 Coding                      0             0        3000

30 Director                    0             0        3000

30 Architect                   0             0        3000

30 Programmer                  0             0        3000

30                             0             1       12000

40 Coding                      0             0        4000

40 Director                    0             0        4000

40 Architect                   0             0        4000

40 Programmer                  0             0        4000

40                             0             1       16000

1             1       40000

21 rows selected.

看出来什么效果了么？

有的同学还是没有看出来，小小的解释一下：

如果显示“1”表示此行对应的这列参与了分组活动

如果显示“0”表示此行对应的这列参未与了分组活动

解释完毕

6.小结

ROLLUP在数据统计和报表生成过程中很有帮助，而且效率比起来union之类的高。这也体现了oracle在SQL统计上人性化、自动化的特点。

另外可以参考oracle官方文档中的例子，链接如下：

《ROLLUP Extension to GROUP BY》

http://download.oracle.com/docs/cd/B19306_01/server.102/b14223/aggreg.htm#i1007413

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