Select Statement yields different result when executed via SQL Server Agent - sql

Question

I am observing a strange behavior on our SQL Server 2014, Standard Edition (64-bit) which I cannot explain:
A simple select statement behaves differently when executed manually or via an SQL Job:
The sql-statement is as follows:
[USE DB2]
GO
Select * from DB1.dbo.price p
where
p.sec_id = 10 and
p.dt = CONVERT(date,getdate() - (case when datename(dw,getdate()) = 'Monday' then 3 else 1 end))
The statement pulls out the price record from table dbo.price for a certain security (sec_id = 10) for the previous business day which normally is 1 day prior, however on Mondays it is 3 days prior as there are only price records on business days available (1 price record per security per business day).
This sql-statement is embedded in a stored procedure which itself is executed via an SQL Server Agent Job.
The strange thing happening is:
If the above sql statement is executed "manually", i.e. via a query editor, it yields the correct result, i.e. one price record is returned when executed Monday to Friday.
The same is true when the above sql statement is executed "manually" via a stored procedure.
However, when the stored procedure containing the above statement is executed via an SQL Server Agent Job, the statement only returns a price record on Tuesday to Friday. On Mondays, the statement returns no record. (Even though the stored procedure respectively the sql statement return a record when executed manually).
Since the job is working Tuesdays to Fridays, it should not be any issue of privileges etc. And since the statement is working when executed manually, there shouldn't be any issue with the statement per se neither.
But why would it not work on a Monday when executed via an SQL job?
Would anybody have an idea what the reason could be? I have none unfortunately ...
Thanks a lot for any help.
Cheers

Answer 1

It's due to the default language of the identity that the Agent job runs under.
In your agent job add this to the script :
SET DATEFIRST 7
[or whatever day of week you expect to be deemed first day of week]
(it's connection specific, so won't affect other connections.)
Or you could change the default language of the login used by SQL Agent (or proxy if you are using one):
USE [master]
GO
ALTER LOGIN [LoginName] WITH DEFAULT_LANGUAGE = [SomeLanguage]
GO
Ref: SET DATEFIRST

Answer 2

As Mitch says, it's likely to be because of different language/date settings used by the Agent job.
My preferred fix though is not to fiddle with settings, but instead to pick a "known good" day with the correct property:
datename(dw,getdate()) = datename(dw,'20150720')
It so happens that 20th July 2015 (selection was entirely arbitrary, I just happen to have a 2015 desk calendar in eyesight) was a Monday and I'm using an unambiguous date format as my literal. So, whetever datename(dw,getdate()) happens to return on Mondays should always be what datename(dw,'20150720') produces.