SQL Clone
SQLServerCentral is supported by Redgate
 
Log in  ::  Register  ::  Not logged in
 
 
 


Datetime precision


Datetime precision

Author
Message
SQLBOT
SQLBOT
SSCrazy
SSCrazy (2K reputation)SSCrazy (2K reputation)SSCrazy (2K reputation)SSCrazy (2K reputation)SSCrazy (2K reputation)SSCrazy (2K reputation)SSCrazy (2K reputation)SSCrazy (2K reputation)

Group: General Forum Members
Points: 2032 Visits: 836
Comments posted to this topic are about the item Datetime precision

Craig Outcalt



Tips for new DBAs: http://www.sqlservercentral.com/articles/Career/64632
My other articles: http://www.sqlservercentral.com/Authors/Articles/Craig_Outcalt/560258
Dude76
Dude76
Old Hand
Old Hand (336 reputation)Old Hand (336 reputation)Old Hand (336 reputation)Old Hand (336 reputation)Old Hand (336 reputation)Old Hand (336 reputation)Old Hand (336 reputation)Old Hand (336 reputation)

Group: General Forum Members
Points: 336 Visits: 94
I will personaly prefer to do something like cast(cast(getdate() as int) as datetime) to obtain de date of the day at midnight rather using datediff+dateadd functions.


My MCP Transcript (ID : 692471 Access : 109741229)
richardd
richardd
Hall of Fame
Hall of Fame (3.2K reputation)Hall of Fame (3.2K reputation)Hall of Fame (3.2K reputation)Hall of Fame (3.2K reputation)Hall of Fame (3.2K reputation)Hall of Fame (3.2K reputation)Hall of Fame (3.2K reputation)Hall of Fame (3.2K reputation)

Group: General Forum Members
Points: 3242 Visits: 648
The wording of this question is ambiguous - if the question is "what would you expect this query to return", then any answer you select is correct by definition, as it's what you would expect. :-P



Lynn Pettis
Lynn Pettis
SSC Guru
SSC Guru (95K reputation)SSC Guru (95K reputation)SSC Guru (95K reputation)SSC Guru (95K reputation)SSC Guru (95K reputation)SSC Guru (95K reputation)SSC Guru (95K reputation)SSC Guru (95K reputation)

Group: General Forum Members
Points: 95335 Visits: 38968
Dude76 (11/30/2009)
I will personaly prefer to do something like cast(cast(getdate() as int) as datetime) to obtain de date of the day at midnight rather using datediff+dateadd functions.


There has been several discussions regarding this and iirc it was actually proven that the dateadd/datediff method is actually faster. Also, it doesn't use the knowledge of how datetime values are stored. If MS changes this, the dateadd/datediff method should still work as advertised.

Cool
Lynn Pettis

For better assistance in answering your questions, click here
For tips to get better help with Performance Problems, click here
For Running Totals and its variations, click here or when working with partitioned tables
For more about Tally Tables, click here
For more about Cross Tabs and Pivots, click here and here
Managing Transaction Logs

SQL Musings from the Desert Fountain Valley SQL (My Mirror Blog)
Carlo Romagnano
Carlo Romagnano
SSCertifiable
SSCertifiable (7.5K reputation)SSCertifiable (7.5K reputation)SSCertifiable (7.5K reputation)SSCertifiable (7.5K reputation)SSCertifiable (7.5K reputation)SSCertifiable (7.5K reputation)SSCertifiable (7.5K reputation)SSCertifiable (7.5K reputation)

Group: General Forum Members
Points: 7532 Visits: 3397
SQLBOT (11/29/2009)
Comments posted to this topic are about the item <A HREF="/questions/Datetime+Manipulation/68075/">Datetime precision</A>

Thanks. After year and years working with sql, there always is something to learn.

I run on tuttopodismo
Peter House
Peter House
SSC-Enthusiastic
SSC-Enthusiastic (145 reputation)SSC-Enthusiastic (145 reputation)SSC-Enthusiastic (145 reputation)SSC-Enthusiastic (145 reputation)SSC-Enthusiastic (145 reputation)SSC-Enthusiastic (145 reputation)SSC-Enthusiastic (145 reputation)SSC-Enthusiastic (145 reputation)

Group: General Forum Members
Points: 145 Visits: 29
While looking at the answer choices, my brain kept saying "Yesterday Midnight + 100ms"

For me, Midnight today is tonight and the SQL answer is this morning at 100ms after midnight or 100ms after the beginning of day.
jim.taylor
jim.taylor
SSC-Enthusiastic
SSC-Enthusiastic (150 reputation)SSC-Enthusiastic (150 reputation)SSC-Enthusiastic (150 reputation)SSC-Enthusiastic (150 reputation)SSC-Enthusiastic (150 reputation)SSC-Enthusiastic (150 reputation)SSC-Enthusiastic (150 reputation)SSC-Enthusiastic (150 reputation)

Group: General Forum Members
Points: 150 Visits: 75
I'm confused, if DateTime is only precise to 3.33 ms, why then is the answer just 1 ms off? Why not 3 ms?
Dude76
Dude76
Old Hand
Old Hand (336 reputation)Old Hand (336 reputation)Old Hand (336 reputation)Old Hand (336 reputation)Old Hand (336 reputation)Old Hand (336 reputation)Old Hand (336 reputation)Old Hand (336 reputation)

Group: General Forum Members
Points: 336 Visits: 94
Lynn Pettis (11/30/2009)
Dude76 (11/30/2009)
I will personaly prefer to do something like cast(cast(getdate() as int) as datetime) to obtain de date of the day at midnight rather using datediff+dateadd functions.


There has been several discussions regarding this and iirc it was actually proven that the dateadd/datediff method is actually faster. Also, it doesn't use the knowledge of how datetime values are stored. If MS changes this, the dateadd/datediff method should still work as advertised.

Oh, faster rather cast, really ?
I didn't know that, and were sure that cast were a fast operation front of manipulating functions.
Thx for the info, i'll test if to have an idea of the difference of performance.


My MCP Transcript (ID : 692471 Access : 109741229)
Go


Permissions

You can't post new topics.
You can't post topic replies.
You can't post new polls.
You can't post replies to polls.
You can't edit your own topics.
You can't delete your own topics.
You can't edit other topics.
You can't delete other topics.
You can't edit your own posts.
You can't edit other posts.
You can't delete your own posts.
You can't delete other posts.
You can't post events.
You can't edit your own events.
You can't edit other events.
You can't delete your own events.
You can't delete other events.
You can't send private messages.
You can't send emails.
You can read topics.
You can't vote in polls.
You can't upload attachments.
You can download attachments.
You can't post HTML code.
You can't edit HTML code.
You can't post IFCode.
You can't post JavaScript.
You can post emoticons.
You can't post or upload images.

Select a forum

































































































































































SQLServerCentral


Search