Question

我有一个查询

WITH a as (
SELECT
      SECTION
    , MAX(PRICE) over w
    , MIN(PRICE) over w
    , AVG(PRICE) over w
    , TIME t, price
    , case when MAX(PRICE) over w = price then TIME end maxt
    , case when MIN(PRICE) over w = price then TIME end mint
FROM s154
WINDOW w as (partition by section)
)
select DISTINCT
      SECTION
    , MAX
    , MIN
    , AVG
    , max(maxt) over (partition by section)
    , min(mint) over (partition by section)
from a;

我决定通过在WITH：

中添加新列来修改我的表

count(*) FROM s154 GROUP BY section.

但是添加group by子句也要求组中的max和min。是否可以在WITH部分查询中计算部分？

Answer 1

您只需添加count(*) over w：

即可

WITH s as (
      SELECT SECTION, MAX(PRICE) over w as max_price,
             MIN(PRICE) over w as min_price, AVG(PRICE) over w as avg_price, 
             TIME as t, price,
             (case when MAX(PRICE) over w = price then TIME end) as maxt
             (case when MIN(PRICE) over w = price then TIME end) as mint,
             (COUNT(*) over w) as cnt
      FROM s154 WINDOW w as (partition by section)
     )
select DISTINCT SECTION, max_price, min_price, avg_price,
       max(maxt) over (partition by section),
       min(mint) over (partition by section),
       cnt
from s;

我非常确定这个查询可以简化。我添加了一些内容，因此更容易理解：

显式列别名。命名您自己的列，它们很重要。
as，所以我可以知道名称的位置。
有意义的CTE名称。＆＃34;＆＃34;在这种情况下毫无意义。至少＆＃34; s＆＃34;是表格的缩写。

我认为更简单的版本是：

      SELECT SECTION, MAX(PRICE) as max_price,
             MIN(PRICE) as min_price, AVG(PRICE) as avg_price, 
             (ARRAY_AGG(time ORDER BY price))[1] as time_at_min_price,
             (ARRAY_AGG(time ORDER BY price DESC))[1] as time_at_max_price
      FROM s154 
      GROUP BY section;

这似乎是表达逻辑的更好方法。

如何将count列添加到查询中？

1 个答案: