I have 12 main heads and all these have 8-12 items in them. User may select values from all of them. I want it to be fast with as minimum space consumed as possible. What i have in mind is:

1. 12 drop down boxes of main heads each containing respective items with multi-select on.

2. first box will contain the main heads. When the user clicks on the head another box will display the items which could be selected then.

I am troubled for the data persistence, to store it in database - should i generate array or what - please help