問題描述
在 SQL Server Management Studio 中運行此命令時
When running this command in SQL Server Management Studio
UPDATE LogChange
SET Created = GETDATE()
WHERE id > 6000
奇怪的事情發生了.. :)
something strange happens.. :)
Created 列中的所有行都獲得相同的值.
All rows get the same value in the Created column.
如何強制"SQL Server 重新計算每一行的 GetDate?
How do I "force" SQL Server to recalculate the GetDate for every row?
推薦答案
如果您想保證將單獨的值應用于每一行，請編寫一個絕對能做到這一點的查詢:
If you want to guarantee that separate values are applied to each row, write a query that definitely does that:
declare @dt datetime
set @dt = GETDATE()
;With Diffs as (
select
*,
ROW_NUMBER() OVER (ORDER BY id) * 10 as Offset
from
LogChange
WHERE id > 6000
)
UPDATE Diffs
SET Created = DATEADD(millisecond,Offset,@dt)
我們知道上面會為每一行生成單獨的偏移量，并且我們肯定會將這些偏移量添加到一個固定值.經常觀察到 GETDATE() 將為所有行返回相同的值，但我找不到任何保證這一點的特定文檔，這就是為什么我還介紹了一個 @dt 變量，以便我知道它只分配一次.
We know that the above will generate separate offsets for each row, and that we're definitely adding those offsets to a fixed value. It has often been observed that GETDATE() will return the same value for all rows but I cannot find any specific documentation that guarantees this, which is why I've also introduced a @dt variable so that I know it's only assigned once.
這篇關于為每一行強制重新計算 GetDate()的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！