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[英]SQL Server : cannot perform an aggregate function on an expression containing an aggregate or a subquery
[英]SQL Server Cannot perform an aggregate function on an expression containing an aggregate or a subquery
我的存儲過程存在問題。
我收到錯誤:
無法對包含聚合或子查詢的表達式執行聚合函數
這是我的存儲過程的一部分,我相信錯誤發生:
SELECT column_1, column_2,
SUM(CASE WHEN column_2 NOT IN (SELECT product FROM table_products) THEN 1
ELSE 0
END) AS Total
FROM my_table
WHERE is_rated = '1'
GROUP BY column_1, column_2
謝謝。
如果您嘗試避免相關子查詢,通常會獲得更好的性能:
SELECT
MT.column_1,
MT.column_2,
SUM(CASE WHEN P.product IS NULL THEN 1 ELSE 0 END) AS total
FROM
My_Table MT
LEFT OUTER JOIN Products P ON P.product = MT.column_2
WHERE
MT.is_rated = '1'
GROUP BY
MT.column_1,
MT.column_2
這假設Products表中最多只有一個匹配項(產品,而不是Table_Products - 當然它是一個表,所以不要把它放在名稱中)。 換句話說,如果product是Products表的PK(或AK),這將起作用。
如果情況並非如此,並且您可能在Products
表中有多個匹配項,那么您可以JOIN
到在product
列上使用DISTINCT
的子查詢。
SELECT
column_1, column_2,
SUM(
CASE
WHEN table_products.product IS NULL THEN 1
ELSE 0
END
) AS Total
FROM my_table
left join table_products on my_table.column_2 = table_products.product
WHERE is_rated = '1'
GROUP BY column_1, column_2
您可以在子查詢中移動SUM()
邏輯:
SELECT t.column_1, t.column_2,
(SELECT COUNT(*)
FROM table_products p
WHERE t.column_2 <> p.product
) as Total
FROM my_table t
WHERE t.is_rated = '1'
GROUP BY t.column_1, t.column_2 ;
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