list() in a case statement

[Former Member]

Wondering if anyone can shed some light on the possibilies of having a list() in a case statement. ex:

select (case
  when [field] = [x] then list([y], [z])
else [a]
end)
from [table]

couldn't find any documentation and the list() function seems a bit limited from the documents info.

Appreciate your help. I'm using sql anywhere 11.

[VolkerBarth · Accepted solution]

LIST does work in a CASE expression. The following is a (not very useful) sample:

select case
  when creator <> 3
  then 'System procs: ' || list(proc_name, ', ' order by proc_name)
  else 'My procs: ' || list(proc_name, ', ' order by proc_name)
end case as MyProcList
from sysprocedure group by creator

Note, however, that LIST is an aggregate function, i.e. the [field] you refer to in the CASE WHEN expression must be part of the GROUP BY clause.

That's the reason I used "GROUP BY creator".

As to your notation of (list[y], [z]): Note that LIST is not a string concatenation, instead it lists all particular values per group. A simple string concatenation can be done with operator || (as in the sample) or the STRING function.

[Former Member · Accepted solution]

Volker, great stuff with the ||. That did the trick. And, I appreciate the notes on LIST. Helped tremendously. Thanks again