Oracle ranking function (Rank) example explanation

This article introduces the Oracle ranking function (Rank) Detailed example, a friend in need can refer

 

- known: two kinds are ranked (no partitions and partition): with and without partition

- two calculations (continuous, discontinuous), the corresponding function: dense_rank, rank

• The query raw data: number, name, account name, score

select * from t_score

 

S_ID	S_NAME	SUB_NAME	SCORE
1	Joe Smith	Chinese	80.00
2	John Doe	mathematics	80.00
1	Joe Smith	mathematics	0.00
2	John Doe	Chinese	50.00
3	Chi Master	Chinese	10.00
3	Chi Master	mathematics
3	Chi Master	physical education	120.00
4	Yang Guo	JAVA	90.00
5	mike	c++	80.00
3	Chi Master	Oracle	0.00
4	Yang Guo	Oracle	77.00
2	John Doe	Oracle	77.00

 

 

· Oracle query subjects for each student ranking (simple ranking)

select sc.s_id,sc.s_name,sub_name,sc.score,

Rank () over  ( Order   by  Score  desc ) Place

from t_score sc

where sub_name='Oracle'

 

 

S_ID	S_NAME	SUB_NAME	SCORE	Ranking
4	Yang Guo	Oracle	77.00	1
2	John Doe	Oracle	77.00	1
3	Chi Master	Oracle	0.00	3

 

 

 

Contrast: rank () and dense_rank (): discontinuous and continuous Rank Rank (it is simple ranking)

 

select sc.s_id,sc.s_name,sub_name,sc.score,

dense_rank() over ( order  by score  desc) 名次

from t_score sc

where  sub_name='Oracle'

 

S_ID	S_NAME	SUB_NAME	SCORE	Ranking
4	Yang Guo	Oracle	77.00	1
2	John Doe	Oracle	77.00	1
3	Chi Master	Oracle	0.00	2

 

 

• The query subjects each student ranking (ranking partition)

select  sc.s_id,sc.s_name,sub_name,sc.score,

rank() over

( Partition   by  sub_name  the Order   by  Score  desc ) ranking

from  t_score sc

 

S_ID	S_NAME	SUB_NAME	SCORE	Ranking
4	Yang Guo	JAVA	90.00	1
4	Yang Guo	Oracle	77.00	1
2	John Doe	Oracle	77.00	1
3	Chi Master	Oracle	0.00	3
5	mike	c++	80.00	1
3	Chi Master	mathematics		1
2	John Doe	mathematics	80.00	2
1	Joe Smith	mathematics	0.00	3
3	Chi Master	physical education	120.00	1
1	Joe Smith	Chinese	80.00	1
2	John Doe	Chinese	50.00	2
3	Chi Master	Chinese	10.00	3

 

• The query before two subjects (partition rank)

· Similar: News table, find the column hits the previous three news.
Product table, find the top 10 of each category of sales of goods.

select * from (
select sc.s_id,sc.s_name,sub_name,sc.score,
dense_rank() over
(partition by sub_name order by score desc) 名次
from t_score sc
) x
where x.名次<=2

 

S_ID	S_NAME	SUB_NAME	SCORE	Ranking
4	Yang Guo	JAVA	90.00	1
4	Yang Guo	Oracle	77.00	1
2	John Doe	Oracle	77.00	1
3	Chi Master	Oracle	0.00	2
5	mike	c++	80.00	1
3	Chi Master	mathematics		1
2	John Doe	mathematics	80.00	2
3	Chi Master	physical education	120.00	1
1	Joe Smith	Chinese	80.00	1
2	John Doe	Chinese	50.00	2

 

 

 

• The query each student scores

select s_id,s_name, sum(score) sum_score  from t_score

group  by s_id,s_name

 

S_ID	S_NAME	SUM_SCORE
1	张三	80.00
2	李四	207.00
3	张三丰	130.00
4	杨过	167.00
5	mike	80.00

 

 

·根据总分查询各同学名次

select x.*,

rank() over ( order  by sum_score  desc) 名次

from (

select s_id,s_name, sum(score) sum_score  from t_score

group  by s_id,s_name ) x

 

S_ID	S_NAME	SUM_SCORE	名次
2	李四	207.00	1
4	杨过	167.00	2
3	张三丰	130.00	3
1	张三	80.00	4
5	mike	80.00	4

 

 

 

语法：

rank() over ( order  by 排序字段 顺序)

rank() over ( partition  by 分组字段  order  by 排序字段 顺序)

 

1.顺序：asc| desc 名次与业务相关：

示例：找求优秀学员：成绩：降序 迟到次数：升序

2.分区字段：根据什么字段进行分区。

 

问题：分区与分组有什么区别?

·分区只是将原始数据进行名次排列(记录数不变),

·分组是对原始数据进行聚合统计(记录数变少,每组返回一条),注意：聚合。

脚本：

create table t_score(
 autoid number primary key,
 s_id  number(3),
 s_name char(8) not null,
 sub_name varchar2(20),
 score number(10,2)
);
insert into t_score (autoid, s_id, s_name, sub_name, score)
values (8, 1, '张三', '语文', 80);
insert into t_score (autoid, s_id, s_name, sub_name, score)
values (9, 2, '李四', '数学', 80);
insert into t_score (autoid, s_id, s_name, sub_name, score)
values (10, 1, '张三', '数学', 0);
insert into t_score (autoid, s_id, s_name, sub_name, score)
values (11, 2, '李四', '语文', 50);
insert into t_score (autoid, s_id, s_name, sub_name, score)
values (12, 3, '张三丰', '语文', 10);
insert into t_score (autoid, s_id, s_name, sub_name, score)
values (13, 3, '张三丰', '数学', null);
insert into t_score (autoid, s_id, s_name, sub_name, score)
values (14, 3, '张三丰', '体育', 120);
insert into t_score (autoid, s_id, s_name, sub_name, score)
values (15, 4, '杨过', 'java', 90);
insert into t_score (autoid, s_id, s_name, sub_name, score)
values (16, 5, 'mike', 'c++', 80);
insert into t_score (autoid, s_id, s_name, sub_name, score)
values (3, 3, '张三丰', 'oracle', 0);
insert into t_score (autoid, s_id, s_name, sub_name, score)
values (4, 4, '杨过', 'oracle', 77);
insert into t_score (autoid, s_id, s_name, sub_name, score)
values (17, 2, '李四', 'oracle', 77);
commit;

 

ending...

 

 

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