check if time is more than 24 hours

hi experts

I have a table Customer which has columns

ID   Name   LastLoggedIn   LoggedInstatus

LastLoggedIn is a timestamp column


I want to come up with a sql which checks
if current time - LastLoggedIn > 24 hours  THEN
update Customer set LoggedInstatus = false

basically the point is if customer is logged in more than 24
hours set the LoggedInstatus  to false

trying to come up with sql , doesnt seem like working

update Customer set LoggedInstatus = false
where
select customer.LastLoggedIn - GETDATE()  from Customer customer  > 24

any help will be appreciated..

thanks.
royjaydAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

lcohanDatabase AnalystCommented:
You will need to use a DATEDIFF function:

http://msdn.microsoft.com/en-us/library/ms189794.aspx

so will be something like:

--update Customer set LoggedInstatus = false
select * from  Customer
where
DATEDIFF ( hour , customer.LastLoggedIn , GETDATE() ) > 24


and this statement will show you the list of records to be updated is you run it against your database - note that I commented out the UPDATE to make sure that's what you want first
0
Jim HornMicrosoft SQL Server Developer, Architect, and AuthorCommented:
Give this a whirl..
UPDATE Customer 
SET LoggedInstatus = false
WHERE DateDiff(hour, LastLoggedIn, GETDATE()) > 24 

Open in new window

or better, so it doesn't compute GETDATE() multiple times
Declare @dt datetime = GETDATE()

UPDATE Customer 
SET LoggedInstatus = false
WHERE DateDiff(hour, LastLoggedIn, @dt) > 24 

Open in new window

0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
royjaydAuthor Commented:
thanks, let me give it a twirl.
0
Scott PletcherSenior DBACommented:
1) NEVER use a function on a column in the WHERE clause if you can avoid it.
2) A computed column might be better for you in this case, as it would always show the current status.

1)
update Customer
set LoggedInstatus = 'false'
where
    LastLoggedIn < DATEADD(HOUR, -24, GETDATE())

2)
ALTER TABLE Customer
ADD LoggedInstatus AS CASE WHEN LastLoggedIn >= DATEADD(HOUR, -24, GETDATE()) THEN 'True' ELSE 'False' END
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Microsoft SQL Server 2008

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.