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[英]SQL Server - CTE/Subqueries performance optimization with window functions
[英]Rewrite query to use window functions except CTE's and subqueries
我有2個相關表格。
package
| id_sort | volume | date |
---------------------------
| int | float | date |
sort
:
| id | id_standard |
---------------------
| int | int |
我需要計算某種排序的體積占sort.id_standard
過濾的總體積的sort.id_standard
。 有CTE的完整查詢
WITH total(volume) AS (
SELECT SUM(package.volume) as volume
FROM package
LEFT JOIN sort ON sort.id = package.id_sort
WHERE
sort.id_standard IN (2,3)
AND package.date >= CONVERT(VARCHAR(7), GETDATE(), 120) + '-01 08:00:00' -- Start of current month
AND package.id_conv <> 12 -- additional filter
), filtered(volume) AS (
SELECT SUM(package.volume) as volume
FROM package
WHERE package.id_sort = 17
AND package.date >= CONVERT(VARCHAR(7), GETDATE(), 120) + '-01 08:00:00' -- start of current month
AND package.id_conv <> 12 -- additional filter
)
SELECT CAST((filtered.volume * 100 / total.volume) AS NUMERIC(3,2)) [percentage] FROM total, filtered;
我敢肯定,窗口函數將在其中發揮最好的作用,但在現實生活中沒有任何經驗。
無需在此處使用window
功能,類似的東西應該會有所幫助
SELECT [percentage] = Cast(( volume * 100 / Nullif(volume,0) ) AS NUMERIC(3, 2))
FROM (SELECT total = Sum(volume),
volume = Sum(CASE WHEN p.id_sort = 17 THEN p.volume ELSE 0 END)
FROM package p
LEFT JOIN sort s
ON s.id = p.id_sort
AND sort.id_standard IN ( 2, 3 )
WHERE p.date >= CONVERT(VARCHAR(7), Getdate(), 120)
+ '-01 08:00:00' -- Start of current month
AND p.id_conv <> 12)a
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