Building a comma separated list?

Question

I\'m tryin to use SQL to build a comma separated list of cat_id\'s

the code is:

declare     @output varchar(max)
set         @output = null;
select @         


        

Answer 1

And sometimes...

you have to answer your own question

declare     @output varchar(max)
select      @output = case when (@output is null) then '' else ', ' END + convert(varchar(max),cat_id)