I'm afraid I don't understand.  Here's a guess, though: alter your function like this:

ALTER FUNCTION [dbo].[test] (@input nvarchar(max))
RETURNS VARCHAR(250)
AS BEGIN
DECLARE @check1 nvarchar(max),
@check2...

Dominik

My advice is to use backup and restore.  It'll be a lot quicker for a big database and it's not susceptible to the issues you're seeing here.  Don't...

Such unpredictability is one of the reasons why I avoid the GUI where possible. But maybe there is logic to it.  A copy-only full backup doesn't have any effect on...

Graeme

That script isn't going to help much here because the plan cache doesn't store the actual execution plan.  You need to either run the query interactively and capture...

Nick

I'm not sure such a reference exists.  My advice is to use T-SQL commands instead of the GUI, and then you know exactly what's going to happen, and...

Without seeing the stored procedure and the actual execution plan, we're just guessing.  Could be any number of things.  Are the actual figures also consistent?  How volatile is your data, and...

Graeme

The execution plan would definitely be a good place to start - the actual execution plan, please, so that we can compare estimated numbers with actual numbers.

Be careful with that query.  It's sensitive to local settings.  As an illustration, try running this:
SET LANGUAGE 'us_english';
SELECT DATEPART(dw,CURRENT_TIMESTAMP);
SET LANGUAGE 'British';
SELECT DATEPART(dw,CURRENT_TIMESTAMP);

I...

Why would you not want to use Upgrade Advisor?  It does precisely what you asked for.  Tell it what database, SSIS packages etc to look in, and it will look...

Something like this:

SELECT c.Traject
FROM tblWebAanvraag w
CROSS APPLY dbo.CreateTrajectCSV(w.AanvraagID) c
WHERE w.Verwijderd = 0

John

Do it like this, and let your presentation layer handle the format of the results, otherwise you'll run into problems like what happens when you have more than 12 rows...

Please will you also show us how you're using the function?  You might get a good performance improvement by rewriting it as an inline table valued function.

John

That's possible, but are your stats really auto-updated so frequently?  I think it's more likely that you have a badly written query that's reading the whole of a large table...