ratio_to_report分析函数求占比

drop table test;
create table test
(
name varchar(20),
kemu varchar(20),
score number
);
insert into test values('testa','yuwen',10);
insert into test values('testa','英语',100);
insert into test values('testb','yuwen',60);
insert into test values('testb','yuwen',120);
insert into test values('testc','yuwen',40);
select name,
score,
ratio_to_report(score) over() as "占所有科目的百分比",
ratio_to_report(score) over(partition by kemu) as "占各科目的百分比"
from test ;

NAME SCORE 占所有科目的百分比 占各科目的百分比
-------------------- ---------- ------------------ ----------------
testa 10 .03030303 .043478261
testb 60 .181818182 .260869565
testc 40 .121212121 .173913043
testb 120 .363636364 .52173913
testa 100 .303030303 1

drop table test;

试想下假设我们没有这个分析函数，实现就有可能如下：

select name,score,
(score/sum(score) over()) as "占所有科目的百分比",
(score/sum(score) over(partition by kemu)) as "占所有科目的百分比"
from test
group by name,score,kemu
order by 2；

嘿嘿，还是没有那个方便，估计效率也不咋的。

总结：1. 有了ratio_to_report分析函数，我们避免了还需要写分析函数，自己相除的写法，SQL简单实现了。

2. site:download.oracle.com ratio_to_report 搜索oracle官方文档