это называется «создание даты и времени», сделайте так, чтобы удалить только время (это самый быстрый метод, более быстрый, чем использование форматирования STING CONVERT () или CAST ()):
DECLARE @datetime datetime;
SET @datetime = '2008-09-17 12:56:53.430';
SELECT DATEADD(day,DATEDIFF(day,0,@datetime),0)
ВЫВОД:
-----------------------
2008-09-17 00:00:00.000
(1 row(s) affected)
вот как это сделать для других частей даты и времени:
--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
ВЫВОД:
-------- -----------------------
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)