在DateTime中删除时间

Question

我有一个问题,我的表存储日期为

2009-01-10 10:00:00.000

我有另一个表存储日期为

2009-01-10 12:00:00.000

我知道它们不一样但是日期是,在SQL中是否可以轻松地缩短时间并保留比较日期？谢谢.

Answer 1

运行这个

SELECT DATEADD(dd, DATEDIFF(d, 0, Getdate()), 0)

将Getdate()更改为列名以删除日期

顺便说一句,如果你进行比较,最好做> =和<,因为它会表现更好

Answer 2

您可以使用以下语法: -

CAST(date_field AS DATE) as column_name

Answer 3

看这里

你想要第一个.

SELECT (CAST(FLOOR(CAST(GETDATE() as FLOAT)) AS DateTime))

不要对varchar使用任何转换,它们很慢.

编辑:@feihtthief - 这是一种从临时数字表中填充日期表(0时间)的方法.如果需要,编辑它以保存数字表.它们也很方便.

DECLARE @DaysFromGoLive int                                                                                 
SET @DaysFromGoLive = (SELECT (DATEDIFF(dd,'10/01/2007',GETDATE()) + 1)) /* Days from go live is the starting date of the table */

 SELECT TOP 10950 --30 years of days                                                                        
        IDENTITY(INT,1,1) as N                                                                              
   INTO #Numbers                                                                                            
   FROM Master.dbo.SysColumns sc1,                                                                          
        Master.dbo.SysColumns sc2                                                                           

CREATE TABLE [dbo].[TableOfDates](                                                                      
    [fld_date] [datetime] NOT NULL,                                                                           
 CONSTRAINT [PK_TableOfDates] PRIMARY KEY CLUSTERED                                                         
(                                                                                                           
    [fld_date] ASC                                                                                            
)WITH FILLFACTOR = 99 ON [PRIMARY]                                                                          
) ON [PRIMARY]                                                                                              


INSERT INTO                                                                                                 
      dbo.TableOfDates                                                                                  
SELECT                                                                                                      
      DATEADD(dd,nums.n - @DaysFromGoLive,CAST(FLOOR(CAST(GETDATE() as FLOAT)) as DateTime)) as FLD_Date    
FROM #Numbers nums                                                                                          

SELECT MIN(FLD_Date) FROM dbo.TableOfDates                                                              
SELECT MAX(FLD_Date) FROM dbo.TableOfDates                                                              

DROP TABLE #Numbers