Hopefully the subject is clear enough.
Let's say I've got two tables:
create_table :bands do | b | b.column :name, :string end
create_table :concerts do | c | c.column :where, :string c.column :when, :date c.column :band_id, :integer end
and the models:
class Band <<ActiveRecord::Base has_many :concerts end
class Concert << ActiveRecord::Base belongs_to :band end
What I'd like to do is find all of the Bands which have at least one concert on or after a given date.
In this case there are lots of concerts which makes this a bit performance critical.
I've not been able to figure out how to do this through ActiveRecord so as to generate an efficient SQL query, or how to do it manually using find_by_sql either. It's a bit complicated also since SQL date comparison function seems to be somewhat database dependent.
Any ideas from the community?