I do apologize if this has already been addressed, but I'm kind of baffled as to why I'm having the problem I am.
Due to some schema issues, I'm having to tease out and glue data together for reports. In one particular report, I'm setting the following:
select @attempt_ids := group_concat(id separator ',') from reporting_v3.attempts where user_id in (@user_ids);
This works, bringing back a comma separated list of values when I use it in mysql.
It works as expected when using that value within a report:
select 'dbr.title', @questionnaire_attempt_ids;
What I can't figure out is how to pass that to a linked report. Is there a way to do this, or will I have to have some duplication in my queries to get the linked reports to work?