Sql 我明白了，这不是真的。查看链接线程以获取更新或直接跳转到。请注意，转换为varchar的速度较慢。请参阅。请注意，转换为varchar的速度较慢。请参阅。请注意，转换为varchar的速度较慢。看。为什么不测试dateadd/datediff呢？因为这不是

---

我明白了，这不是真的。查看链接线程以获取更新或直接跳转到。请注意，转换为varchar的速度较慢。请参阅。请注意，转换为varchar的速度较慢。请参阅。请注意，转换为varchar的速度较慢。看。为什么不测试dateadd/datediff呢？因为这不是OP要求的….？我试过了；这可能会导致错误的结果。虽然这是事实，但问题是关于旧版MS SQL 2000和2005版本，它们缺少

date

数据类型。

Select DateAdd(Day, DateDiff(Day, 0, GetDate()), 0)

Select  DateAdd(Year, DateDiff(Year, 0, GetDate()), 0)
Select  DateAdd(Quarter, DateDiff(Quarter, 0, GetDate()), 0)
Select  DateAdd(Month, DateDiff(Month, 0, GetDate()), 0)
Select  DateAdd(Day, DateDiff(Day, 0, GetDate()), 0)
Select  DateAdd(Hour, DateDiff(Hour, 0, GetDate()), 0)
Select  DateAdd(Second, DateDiff(Second, '20000101', GetDate()), '20000101')

select cast(floor(cast(@datetime as float)) as datetime)

select convert(varchar(10), getdate(), 120)

select convert(datetime, convert(varchar(10), getdate(), 120) , 120)

CONVERT(VARCHAR(10), GETDATE(), 120) AS [YYYY-MM-DD]

SELECT TOP 1000000 CRETS FROM tblMeasureLogv2 
SELECT TOP 1000000 CAST(FLOOR(CAST(CRETS AS FLOAT)) AS DATETIME) FROM tblMeasureLogv2
SELECT TOP 1000000 CONVERT(DATETIME, CONVERT(VARCHAR(10), CRETS, 120) , 120) FROM tblMeasureLogv2 
SELECT TOP 1000000 DATEADD(DAY, DATEDIFF(DAY, 0, CRETS), 0) FROM tblMeasureLogv2

Pure-Select:  422
Floor-cast:   625
String-conv: 1953
DateAdd:      531  

select cast(getdate()as varchar(11))as datetime

select cast(getdate() as date)