query.sql

SELECT "resources".* 
FROM "resources" 
INNER JOIN "resources_tags" ON "resources_tags"."resource_id" = "resources"."id" 
INNER JOIN "tags" ON "tags"."id" = "resources_tags"."tag_id" 
WHERE ("tags"."id" IN (4,16)
AND (SELECT count(*) FROM "tags" WHERE "tags"."id" IN(4,16)) = 2)
GROUP BY "resources"."id" 
ORDER BY "resources"."name" ASC

-- Ryan's new method
SELECT DISTINCT(ti.resource) FROM adw_stg.tag_ids ti
JOIN (SELECT resource, count(id) FROM adw_stg.tag_ids 
WHERE(id IN(4,16))
GROUP BY resource) sq
ON(sq.resource = ti.resource
AND sq.count = 2)