Question

我正在运行查询，我使用LEAD函数计算下一个值。问题是我需要在这个“下一个值”列中删除包含NULL的行。我无法执行WHERE NextProductID IS NULL，因为该列是使用LEAD函数计算的。

示例代码：

SELECT BusinessEntityID, ProductID, LEAD(ProductID) OVER(PARTITION BY BusinessEntityID ORDER BY BusinessEntityID) AS NextProductID
FROM Purchasing.ProductVendor
ORDER BY BusinessEntityID, ProductID

我正在使用AdventureWorks2014。任何帮助将不胜感激！

Answer 1

您可以将查询包装在另一个选择中并在那里执行过滤：

SELECT data.BusinessEntityID, data.ProductID, data.NextProductID
FROM (
    -- Your original SELECT becomes the "table"
    SELECT BusinessEntityID, ProductID, 
        LEAD(ProductID) OVER(PARTITION BY BusinessEntityID ORDER BY BusinessEntityID) AS NextProductID
    FROM Purchasing.ProductVendor
    ORDER BY BusinessEntityID, ProductID
) data
WHERE data.NextProductID IS NOT NULL   -- perform the filtering you need

如何在派生列中排除具有空值的行？

1 个答案: