Question

有没有办法做到这一点，例如在Transact-sql中使用某种条件运算符？

IF @ParentBinaryAssetStructureId = -1
BEGIN
    SET @ParentBinaryAssetStructureId = NULL
END

UPDATE  BinaryAssets.BinaryAssetStructures 
SET     ParentBinaryAssetStructureId = @ParentBinaryAssetStructureId
WHERE   BinaryAssetStructureId = @OriginalBinaryAssetStructureId

Answer 1

USE NULLIF()

UPDATE  BinaryAssets.BinaryAssetStructures 
SET     ParentBinaryAssetStructureId = NULLIF(@ParentBinaryAssetStructureId,-1)
WHERE   BinaryAssetStructureId = @OriginalBinaryAssetStructureId

Answer 2

c语言中的三元（条件）运算符：

x = doSomething ? 5 : 7

将在SQL中以这样的方式编写：

SELECT @x = CASE WHEN @doSomething = 1 THEN 5 ELSE 0 END

可能有多个案例（当条款时）：

SELECT @x = CASE WHEN @doSomething = 1 THEN 5 WHEN @somethingElse = 1 THEN 20 ELSE 0 END

Answer 3

UPDATE  BinaryAssets.BinaryAssetStructures 
SET     ParentBinaryAssetStructureId =
   CASE  ParentBinaryAssetStructureId  
     WHEN -1 THEN NULL
     ELSE ParentBinaryAssetStructureId
   END
WHERE   BinaryAssetStructureId = @OriginalBinaryAssetStructureId

给那个旋转

Transact-sql中的条件运算符

3 个答案: