Setting a default value in collection_select

Hi, Could anybody cast some light on these:

1. How can I set a default value in a collection_select? To be specific, I have a class 'Platform', and I want to set the platform_code (a field of Platform) to be 'ORA' (which exists in the Platform table). I tried many variations of the following code in my view, but in vain: <% @selected = 'ORA' %> <%= collection_select "sac_table_platform", "platform_code", Platform.find(:all, :order => "platform_code"), :platform_code, :platform_code, { :selected => @selected } %>

2. How can I build my own list of collection_select, e.g., a list of three people, say, to show [Adam, Bob, Charley] on the collection_select for the corresponding values ['A', 'B', 'C'] in a table (which already exists), and use it in my view?

Thanks, Arif