Select random record within groups sqlite - sql

Question

I can't seem to get my head around this. I have a single table in SQlite, from which I need to select a random() record for EACH group. So, considering a table such as:
id link chunk
2 a me1
3 b me1
4 c me1
5 d you2
6 e you2
7 f you2
I need sql that will return a random link value for each chunk. So one time I run it would give:
me1 | a
you2 | f
the next time maybe
me1 | c
you2 | d
I know similar questions have been answered but I'm not finding a derivation of one that applies here.
UPDATE:
Nuts, follow up question: so now I need to EXCLUDE rows where a new field "qcinfo" is set to 'Y'.
This, of course, hides rows whenever the random ID hits one where qcinfo = 'Y', which is wrong. I need to exclude the row from being considered in the chunk, but still generate a random record for the chunk if any records have qcinfo <> 'Y'.
select t.chunk ,t.id, t.qcinfo, t.link from table1
inner join
(
select chunk ,cast(min(id)+abs(random() % (max(id)-min(id)))as int) AS random_id
from table1
group by chunk
) sq
on t.chunk = sq.chunk
and t.id = sq.random_id
where qcinfo <> 'Y'

Answer 1

A bit hackish, but it works... See sql fiddle http://sqlfiddle.com/#!2/81e75/7
select t.chunk
,t.link
from table1 t
inner join
(
select chunk
,FLOOR(min(id) + RAND() * (max(id)-min(id))) AS random_id
from table1
group by chunk
) sq
on t.chunk = sq.chunk
and t.id = sq.random_id
Sorry, I thought that you said MySQL.
Here is the fiddle and the code for SQLite
http://sqlfiddle.com/#!5/81e75/12
select t.chunk
,t.link
from table1 t
inner join
(
select chunk
,cast(min(id)+abs(random() % (max(id)-min(id)))as int) AS random_id
from table1
group by chunk
) sq
on t.chunk = sq.chunk
and t.id = sq.random_id

Answer 2

Note that SQLite returns the first value corresponding to a group when we do a group by without an aggregation
select link, chunk from table group by chunk;
Running that you'll get this
me1 | a
you2| d
Now you can make the first value random by randomly sorting the table and then grouping. Here's the final solution.
select link, chunk from (select * from table order by random()) group by chunk;