Dear Denis,

Thanks a lot for the lss, it worked!
However, that's not what I was expecting, sorry for the misleading. What I expected is that one TicketID can only be used for one time, but if we have different TicketID in the URL (custom attribute), then the survey should still be opened for others.

For example, this URL can be used once -  limesurvey.local/limesurvey/index.php/14...rachel@custom.edu.cn
If it's used again, then the user will be screened out.
Then if another user used  limesurvey.local/limesurvey/index.php/14...rachel@custom.edu.cn , the survey should be allowed to submit once.

Not sure if this is possible?
Thanks again.

It's what the lss do …
BUT : remind to use Newtest=Y when you test yourself : we don't update current session when prefilling

Start with newtest=Y&TicketID=123 : OK
Start again with newtest=Y&TicketID=123 : KO

I'm tired now … you must try yourself more …

Look at the data in LimeSurvey: you don't have TicketID=0002 data set when you test without newtest=Y

Thanks a million Denis, YOU SAVE MY WEEK! this works just like a charm!
I was struggling with this case for the whole week, even after work hours. This forum is also amazing and more than helpful!

Thanks again and I will spend more time to study this amazing limesurvey:)

Dear Joffm,

With the help from Denis, I've solved the issue mentioned in this topic. I didn't think about using a new question to screen out could be a solution:(

Thanks again for all your help, it means a lot! Cheers.

Well, again the workflow:
1. You want to screen out respondents who already submitted the survey with this TicketID
2. Of course you screen out respondents who use a link without these additional parameters (what may give an answer to your other question)

To do this you use "quotas" with limit "0" 
[url] www.limesurvey.org/manual/Survey_quotas/en [/url]

You can set a quota on an equation, but you have to create a well defined value.

To do this you use the IF-function. As you read in the manual
[url] www.limesurvey.org/manual/ExpressionScri...mplemented_functions [/url]
This function works like human language: if(test,result_if_true,result_if_false)
"IF the sun is shining (condition) I jump into the swimmingpool (what happens if the condition is TRUE) otherwise I read a book (what happens if the condition is FALSE)" 


In your case "IF the function 'statCountif' returns 0, set the value of the equation to 0 ELSE set the value to 1"
Now you have a condition for the quota "if equation==1" --> screenout.

The same to test if there were any additional parameters in the URL.
Here you may use the function "is_empty"
IF the question "TicketID" is empty, set the value of the equation to 1 ELSE set the value to 0"
Again you have a condition for the (second) quota "if equation==1" --> screenout.


So the survey could look like this


Joffm

And here the lss