Window 函数未给出总计运行

Question

在以下查询中：

SELECT
 d.date,
 d.location,
 d.population,
 v.new_vaccinations,
 SUM(CAST(v.new_vaccinations AS int)) OVER (PARTITION BY d.location) AS total_vaccinations
FROM
 CovidDeaths d
JOIN
 CovidVaccinations v
ON
 d.date = v.date
 AND
 d.location = v.location
WHERE  
 d.continent IS NOT NULL
ORDER BY 
 d.location,
 d.date

window 函数只是根据日期给出每个位置的总数，而不是运行总数。我做错了什么？

Answer 1

要获得运行累计总数，必须在 OVER 中指定或暗示 RANGE 或 ROWS window，因此 你还需要添加一个ORDER BY。否则 window 是完整分区。

一旦您指定 ORDER BY，默认隐含的 window 是 RANGE UNBOUNDED PRECEDING，对于来自 ROWS.

鉴于 date 可能不是唯一的，您还需要 ROWS UNBOUNDED PRECEDING.

SELECT
 d.date,
 d.location,
 d.population,
 v.new_vaccinations,
 SUM(CAST(v.new_vaccinations AS int))
    OVER (PARTITION BY d.location ORDER BY d.date ROWS UNBOUNDED PRECEDING) AS total_vaccinations
FROM
 CovidDeaths d
JOIN
 CovidVaccinations v
ON
 d.date = v.date
 AND
 d.location = v.location
WHERE  
 d.continent IS NOT NULL
ORDER BY 
 d.location,
 d.date

Window 函数未给出总计运行

Window function not giving running total

sql-server

window-functions

Window 函数未给出总计 运行

Window function not giving running total

sql-server

window-functions

Window 函数未给出总计运行