Question

我根据下表中的两列编写了一份相当简单的报告如果is_sender为true，则在报告中添加一行“sender” 如果两者都打开，则将两条记录添加到报告中因此，对于以下数据，结果如下：

sender, Robert
receiver,Robert
receiver,Marco

我使用“with子句”和结果联合实现了所需的报告，但其性能非常糟糕，

有没有办法使用分析功能或更好的方法来做同样的事情？

create table users_table(
    name varchar2(10),
    is_sender char(1),
    is_receiver char(1)
)

insert into users_table values('Robert','y','n');
insert into users_table values('Marco','y','y');

create or replace  view users_view ("role", "name") as 
(
   select role,name from (
    with sender_reciver_view as (select name,is_sender,is_receiver from users_table)
select 'sender' as role,name from sender_reciver_view where is_sender='y'
   union all
select 'receiver',name from sender_reciver_view where is_receiver='y')
)

Answer 1

我假设在你的例子中，Marco应该有两行，对吗？

select
  m.role,
  ut.name
from users_table ut
  join (
    select 'sender' as role from dual union all
    select 'receiver' from dual
  ) m
  on (m.role = 'sender' and ut.is_sender = 'y')
  or (m.role = 'receiver' and ut.is_receiver = 'y');

结果：

ROLE     NAME
sender   Robert
sender    Marco
receiver  Marco

使用with子句时报告性能

1 个答案: