//tagchain AND

select name from bands where id in
(select band_id from tagged where tag_id in (select id from tags where name = 'black metal'))
and id in
(select band_id from tagged where tag_id in (select id from tags where name = 'norway'))
ORDER BY name

//tagchain OR

select name from bands where id in
(select band_id from tagged where tag_id in (select id from tags where name = 'black metal'))
OR id in
(select band_id from tagged where tag_id in (select id from tags where name = 'norway'))
ORDER BY name