select statment with field select as (what is this called?)

Question

Here is an example what I am trying to do:

I have to organize a list of events by month/year with the count of the events, then a comma list of the IDs of those events.

Here is what I have:

     SELECT count(*) as counter, 
                   MONTHNAME(publishDate) as month, 
                   YEAR(publishDate) as year 
              FROM bursch.events 
     GROUP BY YEAR(publishDate), 
              MONTH(publishDate) 
     order by year desc;

BUT, in addition, I need those IDs too (2,5,6) <<< like this:

Here is the concept:

SELECT count(*) as counter, 
       MONTHNAME(publishDate) as month, 
       YEAR(publishDate) as year,
       (select id 
          from events 
          where 'call conditions affect the main query') as IDList 
              FROM events 
     GROUP BY YEAR(publishDate), 
              MONTH(publishDate) 
     order by year desc;

Which would result in something like this:

counter  |  month   | year  | ids
-----------------------------------------
3        |  June    | 2013  | 45,49,50
4        |  July    | 2013  | 39,40,41,42
2        |  March   | 2011  | 33,34
5        |  May     | 2011  | 27,29,30,31,32
1        |  June    | 2011  | 22
4        |  July    | 2011  | 14,17,18,19
1        |  January | 2010  | 13

It would be great of I can base my select results on the conditions of the main select statement. There may be a better way to get this result. Maybe a simpler method. But the select as field part. What would that be called? Correlated query? Not sure. I have seen that I can do that in Oracle and MySQL and it comes in handy (if I only knew what it is called).

Thanks in advanced. Let me know if something is unclear.

Answer 1

MySQL has a function called GROUP_CONCAT() which concatenates rows instead of columns.

SELECT COUNT(*) as counter, 
       MONTHNAME(publishDate) as month, 
       YEAR(publishDate) as year,
       GROUP_CONCAT(id) as IDs
FROM   events 
GROUP  BY YEAR(publishDate), 
          MONTH(publishDate) 
ORDER  BY year desc;