[Last Call] Learn about multicloud storage options and how to improve your company's cloud strategy. Register Now

x
?
Solved

CAST(date_column + time_column as datetime)

Posted on 2016-07-27
8
Medium Priority
?
54 Views
Last Modified: 2016-07-27
Hi guys

Question for you:  What's the fastest way to add a date column and a time column and cast it as a single datetime column?

Example:
Declare @dt date = '20160727', @tm time = '03:30:00'
SELECT CAST( ???? as datetime) 

Open in new window


Thanks in advance.
Jim
0
Comment
Question by:Jim Horn
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
8 Comments
 
LVL 13

Assisted Solution

by:Dustin Saunders
Dustin Saunders earned 1000 total points
ID: 41731778
I use:
SELECT CONVERT(DATETIME, CONVERT(CHAR(8), @dt, 112) 
  + ' ' + CONVERT(CHAR(8), @tm, 108))

Open in new window

0
 
LVL 6

Expert Comment

by:Manuel Marienne-Duchêne
ID: 41731781
CAST(@dt + @tm AS DATETIME) with space in first position in time
0
 
LVL 13

Expert Comment

by:Dustin Saunders
ID: 41731811
But don't you need extra steps to add in the space in time (say if it were from a column)?  [maybe we should add physics to the categories if we're talking about spacetime :P ]

Anyways, I guess if I used it a lot I'd just stick it in a UDF and call that when needed (seems easiest for me though I don't know if there's a more performance efficient way?)

CREATE FUNCTION concatDT (@dt date,@tm time)
RETURNS datetime
AS
BEGIN
RETURN(	SELECT CONVERT(DATETIME, CONVERT(CHAR(8), @dt, 112) 
	+ ' ' + CONVERT(CHAR(8), @tm, 108)))
END

Open in new window

SELECT dbo.concatDT(@dt,@tm)

Open in new window

0
Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 70

Accepted Solution

by:
Scott Pletcher earned 1000 total points
ID: 41731997
SELECT CAST(@dt AS datetime) + @tm
0
 
LVL 13

Expert Comment

by:Dustin Saunders
ID: 41732007
I tried:
Declare @dt date = '20160727', @tm time = '03:30:00'
SELECT CAST(@dt AS datetime) + @tm

Open in new window

and got:
Msg 402, Level 16, State 1, Line 2
The data types datetime and time are incompatible in the add operator.


but
Declare @dt date = '20160727', @tm time = '03:30:00'
SELECT CAST(@dt AS datetime) + CAST(@tm AS datetime)

Open in new window


does work and is less code than mine.
0
 
LVL 70

Expert Comment

by:Scott Pletcher
ID: 41732066
I tried:
Declare @dt date = '20160727', @tm time = '03:30:00'
SELECT CAST(@dt AS datetime) + @tm
and got [an error]

Hmm, worked fine for me, at least through SQL 2012.  Maybe that's a later SQL version restriction?  I know they've made some changes in that area.
0
 
LVL 66

Author Closing Comment

by:Jim Horn
ID: 41732074
Thanks guys.  Chose Scott's answer as it was a less expensive option, which works on my 2008R2 box.
0
 
LVL 13

Expert Comment

by:Dustin Saunders
ID: 41732077
Yeah, I agree that's better way.  It's weird that it doesn't run on my SQL test servers (I tried on SQL 2012 SP3 and 2014); so must have appeared somewhere around there, or maybe I angered some vengeful SQL God.

Might be a good note or item to test though, in case you upgrade production SQL versions in the future it might break the query.
0

Featured Post

Microsoft Certification Exam 74-409

Veeam® is happy to provide the Microsoft community with a study guide prepared by MVP and MCT, Orin Thomas. This guide will take you through each of the exam objectives, helping you to prepare for and pass the examination.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

I have a large data set and a SSIS package. How can I load this file in multi threading?
One of the most important things in an application is the query performance. This article intends to give you good tips to improve the performance of your queries.
Via a live example, show how to setup several different housekeeping processes for a SQL Server.
Viewers will learn how to use the SELECT statement in SQL to return specific rows and columns, with various degrees of sorting and limits in place.

650 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question