+NOTE:Dynamic finders have been deprecated inRails4.0and will be removed inRails4.1. The best practice is to use ActiveRecord scopes instead. You can find the deprecation gem at https://github.com/rails/activerecord-deprecated_finders
For every field (also known as an attribute) you define in your table, ActiveRecord provides a finder method. If you have a field called `first_name` on your `Client` model for example, you get `find_by_first_name`for free from ActiveRecord. If you have a `locked` field on the `Client` model, you also get `find_by_locked`and methods.
You can specify an exclamation point (`!`) on the end of the dynamic finders to get them to raise an `ActiveRecord::RecordNotFound` error if they do notreturn any records, like `Client.find_by_name!("Ryan")`