Date add assistance please? - SQL Server Forums

Please start any new threads on our new site at https://forums.sqlteam.com. We've got lots of great SQL Server experts to answer whatever question you can come up with.

All Forums

SQL Server 2012 Forums

Transact-SQL (2012)

Date add assistance please?

Author

Topic

MelissaTsalicoglou
Starting Member

16 Posts

Posted - 2014-06-04 : 09:53:10

Hi All
Would it be possible to explain what the -DAY calculates?

DATEADD(day, -DAY(current_timestamp) +1, current_timestamp) as firstday

Best Regards
Melissa

khtan
In (Som, Ni, Yak)

17689 Posts

Posted - 2014-06-04 : 10:26:24

run this and see the result


SELECT 	current_timestamp,
	-DAY(current_timestamp),
	DATEADD(day, -DAY(current_timestamp) +1, current_timestamp) as firstday

KH
[spoiler]Time is always against us[/spoiler]

webfred
Master Smack Fu Yak Hacker

8781 Posts

Posted - 2014-06-04 : 10:26:31

to get the first day of the actual month this solution subtracts the actual days and then adds 1 day.

2014-06-04 -4 +1 = 2014-06-01

dateadd() used with a negative value to add is like you have a function datesubtract()

:)

Too old to Rock'n'Roll too young to die.

MelissaTsalicoglou
Starting Member

16 Posts

Posted - 2014-06-04 : 10:48:46

ok so '- Day' subtracts all the days from the current date of that month ? giving you the last day of the previous month? then you add 1 day to get to the first day of the month?

quote:
Originally posted by webfred

to get the first day of the actual month this solution subtracts the actual days and then adds 1 day.

2014-06-04 -4 +1 = 2014-06-01

dateadd() used with a negative value to add is like you have a function datesubtract()

:)

Too old to Rock'n'Roll too young to die.