Users who favourited this also favourited this

Question

hi i am trying to set up a system similar to amazons, whereby
when you search a book, it tells you Customers who bought this item
also bought these items( a list of other books)
What i am trying to do is have a system which tells you
"users who have favourited this musician have also favourited these
artists"...
At the moment I have a query which takes an artists primary
id from the url of thier page, and the users primary id who
favourited the artist, and puts this into a table, so then you can
call the users fav artists, using
SELECT *
FROM artists_fav
WHERE id_usr_fav=#SESSION.auth.idnumber#
But im unsure of how to write a query that would take all the
other artists that a user has, who has favourited "massive attack"
for example, and present this in a list whereby the artist who has
been favourited the most by users who have also favourited massive
attack is at the top, then the next popular is second etc
here my site
http://www.musicexplained.co.uk/index_artist.cfm?id_art=38
and if you would like to test the favouriting system, you can
use username blanko, and password dranko
any help here would be MUCH appreciated

Answer 1

hi, following your advice i have pretty much got this up and
running, the only thing is, that when i try and run the count
(bandname_art) as favourite in the query i get an error message
so
<!---similar artists--->
<cfquery name="sim_art"
datasource="#APPLICATION.DataSource#">
SELECT bandname_art
FROM artist_art
LEFT OUTER JOIN artists_fav
ON artist_art.id_art = artists_fav.id_artkey_fav
WHERE id_usr_fav IN
(select id_usr_fav
from artists_fav
where id_usr_fav <> #session.auth.idnumber#
AND id_artkey_fav = #url.id_art#)
AND id_art <>#url.id_art#
</cfquery>
is fine
but
<!---similar artists--->
<cfquery name="sim_art"
datasource="#APPLICATION.DataSource#">
SELECT bandname_art, count (bandname_art) as favourite_count
FROM artist_art
LEFT OUTER JOIN artists_fav
ON artist_art.id_art = artists_fav.id_artkey_fav
WHERE id_usr_fav IN
(select id_usr_fav
from artists_fav
where id_usr_fav <> #session.auth.idnumber#
AND id_artkey_fav = #url.id_art#)
AND id_art <>#url.id_art#
</cfquery>
returns the error message of "You tried to execute a query
that does not include the specified expression 'bandname_art' as
part of an aggregate function."
i was wondering there was another way to order by favourite
count...maybe by using another query in conjuction etc etc
cheers