Question

我创建的存储过程有效，但是有更有效的方法吗？公平地说，没有任何性能损失，也不需要优化，但我想知道为了正确地做事。

执行计划声明query 1: 17%，query 2: 67%，query 3: 16%

DECLARE @CurrentVoucherID int;

SET @CurrentVoucherID  = 
    (
        SELECT TOP(1) IdGiftVoucherPhysicalCode 
        from GiftVoucherPhysicalCodes
        WHERE Activated = 0 and assigned = 0 and Value = 10
        ORDER BY IdGiftVoucherPhysicalCode
    );

UPDATE GiftVoucherPhysicalCodes
SET Activated = 1, Activated_at = GETDATE()
WHERE IdGiftVoucherPhysicalCode = @CurrentVoucherID;

SELECT * FROM GiftVoucherPhysicalCodes
WHERE IdGiftVoucherPhysicalCode = @CurrentVoucherID;

Answer 1

我可能无法正确理解它，但看起来您只是一次运行更新一条记录？为什么不批量做？

UPDATE GiftVoucherPhysicalCodes
SET Activated = 1, Activated_at = GETDATE()
WHERE Activated = 0 and assigned = 0 and Value = 10

Answer 2

你可以不用变量

来做

UPDATE GiftVoucherPhysicalCodes
SET Activated = 1, Activated_at = GETDATE()
WHERE IdGiftVoucherPhysicalCode = (SELECT TOP(1) IdGiftVoucherPhysicalCode 
                            from GiftVoucherPhysicalCodes
                            WHERE Activated = 0 and assigned = 0 and Value = 10
                            ORDER BY IdGiftVoucherPhysicalCode)

SELECT * FROM GiftVoucherPhysicalCodes
WHERE IdGiftVoucherPhysicalCode = (SELECT TOP(1) IdGiftVoucherPhysicalCode 
                            from GiftVoucherPhysicalCodes
                            WHERE Activated = 1 and assigned = 0 and Value = 10
                            ORDER BY IdGiftVoucherPhysicalCode)

优化存储过程更新和选择

2 个答案: