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