SQL 发现不匹配的加入

Question

我有两个表“SellerDetails”和“ANL”，它们的关键字段都是“Seller Ref No”和“Sales Year”。

这让我找到销售年份为“20”且部门为“远程销售”的卖家参考号匹配项

SELECT si.[Seller Ref No] FROM dbo.SellerDetails AS si, dbo.ANL AS a
WHERE si.[Seller Ref No] = a.[Seller Ref No]
AND si.Department = 'Remote Sales'
AND si.[Sales Year] = '20';

但是我如何找出“SellerDetails”中的记录，而不是在“ANL”中的记录，其中销售年份为“20”且部门为“远程销售” “？我已经试过了，但它 returns 的数量比我预期的要大得多。我也尝试过将“=”更改为“<>”，但结果更糟

SELECT si.[Seller Ref No]
FROM dbo.SellerDetails AS si
LEFT JOIN dbo.ANL AS a ON (si.[Seller Ref No] = a.[Seller Ref No])
WHERE si.Department = 'Remote sales'
AND si.[Sales Year] = '20';

Answer 1

您可以使用 not exists:

select s.*
from dbo.SellerDetails s
where 
    s.Department = 'Remote Sales'
    and s.[Sales Year] = 20
    and not exists (select 1 from dbo.ANL a where a.[Seller Ref No] = s.[Seller Ref No])

不清楚您是否也想使用 [Sales Year] 作为关联条件：它存在于两个表中，但您的查询不使用该关系。如果你想要，那么：

select s.*
from dbo.SellerDetails s
where 
    s.Department = 'Remote Sales'
    and s.[Sales Year] = 20
    and not exists (select 1 from dbo.ANL a where a.[Seller Ref No] = s.[Seller Ref No] and a.[Sales Year] = s.[Sales Year])

旁注：这是您可能想要使用 left join:

编写的查询

SELECT si.[Seller Ref No]
FROM dbo.SellerDetails AS si
LEFT JOIN dbo.ANL AS a ON si.[Seller Ref No] = a.[Seller Ref No]
WHERE 
    si.Department = 'Remote sales'
    AND si.[Sales Year] = '20'
    AND a.[Seller Ref No] IS NULL

WHERE 子句中的最后一个条件过滤掉匹配的行。

Answer 2

SELECT si.[Seller Ref No]
FROM dbo.[SellerDetails] AS   si
LEFT JOIN dbo.[ANL] AS a ON   si.[Seller Ref No] = a.[Seller Ref No]
                     AND   si.[Department] = 'Remote sales'
                     AND   si.[Sales Year] = '20'
Where a.[Seller Ref No] is null

SQL 发现不匹配的加入

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