根據空值查詢的結果將列更新爲BIT值

Question

我試圖編寫一個查詢來根據另一列是否爲空來設置一個位值。

例如：

UPDATE @tmpRank 
SET IsXYSale = NOT dbo.Sales_XForY.ID IS NULL 
FROM @tmpRank 
LEFT JOIN dbo.Sales_XForY ON SaleId = @tmpRank.SaleId 

我得到的不是關鍵字語法錯誤，但我看不出如何糾正查詢。

Answer 1

SET IsXYSale = CASE WHEN dbo.Sales_XForY.ID IS NULL THEN 0 ELSE 1 END 

Answer 2

UPDATE @tmpRank 
SET IsXYSale = CASE WHEN dbo.Sales_XForY.ID IS NULL THEN 0 ELSE 1 END 
FROM @tmpRank 
LEFT JOIN dbo.Sales_XForY ON SaleId = @tmpRank.SaleId 

Answer 3

SQL Server有沒有隱含的布爾

UPDATE @tmpRank 
SET IsXYSale = CASE WHEN dbo.Sales_XForY.ID IS NULL THEN 0 ELSE 1 END 
FROM @tmpRank 
LEFT JOIN dbo.Sales_XForY ON SaleId = @tmpRank.SaleId 

在這種情況下，您可以利用位是如何工作的：任何非零，非空值變爲1.假設你絕不能有0作爲當然的ID值...

SET IsXYSale = ISNULL(dbo.Sales_XForY.ID, 0)