Getting the 'date' out of a DateTime field in SQL Server

Question

I have a date column where the date is displayed in the format 2009-11-18 10:55:28.370.

I just want to get the date (not time) out of that value. How do I do that?

Answer 1

If you're using SQL Server 2008, there is now a DATE datatype. Makes it a lot more natural!

SELECT CONVERT(Date, GETDATE())

Answer 2

it is called "flooring a datetime", do it like this to remove just the time (this is the fastest method, faster than using CONVERT() or CAST() sting formatting):

DECLARE @datetime datetime;
SET @datetime = '2008-09-17 12:56:53.430';
SELECT DATEADD(day,DATEDIFF(day,0,@datetime),0)

OUTPUT:

-----------------------
2008-09-17 00:00:00.000

(1 row(s) affected)

here is how to do it for other parts of a datetime:

--Floor a datetime
DECLARE @datetime datetime;
SET @datetime = '2008-09-17 12:56:53.430';

SELECT '0 None',  @datetime                                                                   -- none    2008-09-17 12:56:53.430
UNION SELECT '1 Second',DATEADD(second,DATEDIFF(second,'2000-01-01',@datetime),'2000-01-01')  -- Second: 2008-09-17 12:56:53.000
UNION SELECT '2 Minute',DATEADD(minute,DATEDIFF(minute,0,@datetime),0)                        -- Minute: 2008-09-17 12:56:00.000
UNION SELECT '3 Hour',  DATEADD(hour,DATEDIFF(hour,0,@datetime),0)                            -- Hour:   2008-09-17 12:00:00.000
UNION SELECT '4 Day',   DATEADD(day,DATEDIFF(day,0,@datetime),0)                              -- Day:    2008-09-17 00:00:00.000
UNION SELECT '5 Month', DATEADD(month,DATEDIFF(month,0,@datetime),0)                          -- Month:  2008-09-01 00:00:00.000
UNION SELECT '6 Year',  DATEADD(year,DATEDIFF(year,0,@datetime),0)                            -- Year:   2008-01-01 00:00:00.000
ORDER BY 1
PRINT' '
PRINT 'Note that when you are flooring by the second, you will often get an arithmetic overflow if you use 0. So pick a known value that is guaranteed to be lower than the datetime you are attempting to floor'
PRINT 'this always uses a date less than the given date, so there will be no arithmetic overflow'
SELECT '1 Second',DATEADD(second,DATEDIFF(second,DATEADD(day,DATEDIFF(day,0,@datetime),0)-1,@datetime),DATEADD(day,DATEDIFF(day,0,@datetime),0)-1)  -- Second: 2008-09-17 12:56:53.000

OUTPUT:

-------- -----------------------
0 None   2008-09-17 12:56:53.430
1 Second 2008-09-17 12:56:53.000
2 Minute 2008-09-17 12:56:00.000
3 Hour   2008-09-17 12:00:00.000
4 Day    2008-09-17 00:00:00.000
5 Month  2008-09-01 00:00:00.000
6 Year   2008-01-01 00:00:00.000

(7 row(s) affected)


Note that when you are flooring by the second, you will often get an arithmetic overflow if you use 0. So pick a known value that is guaranteed to be lower than the datetime you are attempting to floor
this always uses a date less than the given date, so there will be no arithmetic overflow

-------- -----------------------
1 Second 2008-09-17 12:56:53.000

(1 row(s) affected)