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sql-server – 如果参数为null,则SQL select all all返回特定项

 5 years ago
source link: https://codeday.me/bug/20190112/508961.html?amp%3Butm_medium=referral
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有没有办法编写以下脚本,以便在ProductID变量为null时返回所有产品？并在产品不为空时返回特定产品.

到目前为止我所拥有的：

DECLARE @productID INT = NULL

SELECT
    ProductID,
    ProductName,
    ProductDesc 
FROM
    product 
WHERE
    ProductID = @productID

用例陈述：

SELECT ProductID, ProductName,ProductDesc 
FROM product 
WHERE ProductID = CASE WHEN @productID IS NULL THEN ProductID ELSE @productID END

或者IIF()函数,如果您使用的是SQL Server 2012：

SELECT ProductID, ProductName,ProductDesc 
FROM product 
WHERE ProductID =IIF(@productID IS NULL, ProductID, @productID )

翻译自：https://stackoverflow.com/questions/19357990/sql-select-all-if-parameter-is-null-else-return-specific-item


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