Oracle分析函数 — sum, rollup, cube, grouping用法

本文通过例子展示sum, rollup, cube, grouping的用法。

//首先建score表

create table score(

class nvarchar2(20),

course nvarchar2(20),

stu_no number(5),

stu_name nvarchar2(20),

score number(2));

//插入数据

insert into score values ('Class_A','Math',10001,'Tough1',95);

insert into score values ('Class_A','Math',10002,'Tough2',93);

insert into score values ('Class_B','Math',10003,'Tough3',94);

insert into score values ('Class_B','Math',10004,'Tough4',88);

insert into score values ('Class_A','Computer',10001,'Tough1',89);

insert into score values ('Class_A','Computer',10002,'Tough2',98);

insert into score values ('Class_B','Computer',10003,'Tough3',89);

insert into score values ('Class_B','Computer',10004,'Tough4',87);

SELECT * FROM score;

CLASS	COURSE	STU_NO	STU_NAME	SCORE
Class_A	Math	10001	Tough1	95
Class_A	Math	10002	Tough2	93
Class_B	Math	10003	Tough3	94
Class_B	Math	10004	Tough4	88
Class_A	Computer	10001	Tough1	89
Class_A	Computer	10002	Tough2	98
Class_B	Computer	10003	Tough3	89
Class_B	Computer	10004	Tough4	87

sum函数

按class,course分组，然后对score统计总合

CLASS	COURSE	AVG_SCORE
Class_B	Math	91
Class_A	Computer	93.5
Class_A	Math	94
Class_B	Computer	88

rollup函数

先按class,course分组汇总;再按class分组汇总;最后全表分组汇总

CLASS	COURSE	AVG_SCORE
Class_A	Math	94
Class_A	Computer	93.5
Class_A		93.75
Class_B	Math	91
Class_B	Computer	88
Class_B		89.5
		91.625

cube函数

先按class,course分组汇总;再按class分组汇总;再按course分组汇总;最后全表分组汇总

CLASS	COURSE	AVG_SCORE
Class_A	Computer	93.5
Class_A	Math	94
Class_A		93.75
Class_B	Computer	88
Class_B	Math	91
Class_B		89.5
	Computer	90.75
	Math	92.5
		91.625

rollup和cube区别：

ROLLUP(A,B,C)的话，GROUP BY顺序

(A,B,C)

(A,B)

(A)

最后对全表进行GROUP BY操作。

GROUP BY CUBE(A, B, C)，GROUP BY顺序

(A,B,C)

(A,B)

(A,C)

(A)，

(B,C)

(B)

(C)，

最后对全表进行GROUP BY操作。

grouping函数

rollup和cube函数都会对结果集产生null，这时候可用grouping函数来确认该记录是由哪个字段得出来的。grouping函数用法，带一个参数，参数为字段名，结果是根据该字段得出来的就返回1，反之返回0

CLASS	COURSE	AVG_SCORE
All Class	All Course	91.625
All Class	Computer	90.75
All Class	Math	92.5
Class_A	All Course	93.75
Class_A	Computer	93.5
Class_A	Math	94
Class_B	All Course	89.5
Class_B	Computer	88
Class_B	Math	91