如何在 PostgreSQL 中创建命名窗口分区（别名）？

发布于 2024-09-13 23:13:23 字数 462 浏览 9 评论 0原文

PostgreSQL 窗口函数的文档似乎意味着您可以在查询中的多个位置使用相同的命名窗口。但是，我不知道如何创建命名窗口？

SELECT first_value(vin) OVER( PARTITION BY vin ) AS w, first_value(make) OVER w
FROM inventory.vehicles
WHERE lot_Id = 9999 AND make is not null;

这是一个笑话查询，我试图获取要采用的语法，但出现错误：

错误：窗口“w”不存在

原文

The documentation for PostgreSQL window functions seems to imply you can use the same named window in multiple places in your query. However, I can't figure out how do I create a named window?

SELECT first_value(vin) OVER( PARTITION BY vin ) AS w, first_value(make) OVER w
FROM inventory.vehicles
WHERE lot_Id = 9999 AND make is not null;

This is a joke query I'm trying to get the syntax to take, but I'm getting error:

ERROR: window "w" does not exist

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奢欲 2024-09-20 23:13:23

答案实际上在 SELECT 文档：

WINDOW子句
可选的WINDOW子句具有
一般形式
WINDOW 窗口名称 AS ( window_definition ) [, ...]

这是一个示例，

SELECT first_value(vin) OVER w,
  first_value(make) OVER w
FROM inventory.vehicles
WHERE lot_Id = 9999
  AND make is not null
WINDOW w AS ( PARTITION by vin );

The answer was actually in the SELECT doc:

WINDOW Clause
The optional WINDOW clause has the
general form
WINDOW window_name AS ( window_definition ) [, ...]

Here is an example,

SELECT first_value(vin) OVER w,
  first_value(make) OVER w
FROM inventory.vehicles
WHERE lot_Id = 9999
  AND make is not null
WINDOW w AS ( PARTITION by vin );

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