在查询中基于一个 select 的两个选择

Question

我可以做一个 select 然后在一个查询中对结果进行不同的选择吗？

现在我想做类似的事情（这是行不通的）

select 
    (select count(*), sum(amount) from view where amount > 5), 
    (select count(*), sum(amount) from view where amount < 5) 
from 
    (select id, amount from warehouse where createDate = '2019-01-01') as view;

我不想 select 视图然后 select 一些数据与基于视图的附加过滤。

Answer 1

您可以使用条件聚合：

select count(*), 
       sum(amount) filter (where waga > 5),
       sum(amount) filter (where amount < 5) 
from warehouse 
where createdate = date '2019-01-01'

Answer 2

关于您可以使用 WITH 子句的一般语法问题：

with v as
(
 select id, amount from warehouse where createDate = '2019-01-01'
)
select * from
(
    (select count(*), sum(amount) from v where waga > 5) as count1, 
    (select count(*), sum(amount) from v where amount < 5) as count2
);

（我并不是说它会更快；这只是一种使用“内联”视图的方法）。