Does this call for an array?

Here is what I would like to do. I have a simple form that asks for information from a customer. One of the questions is Which categories of products are you interested in? I want to store all the data in a table called pf_survey. All the categories(42) are already listed in a separate table called categories. I don't think I want to repeat a list of columns in the pf_survey table if they are already in the categories table. The categories table is simply category_id and category_name. If my form has a checkbox by each category name with the corresponding category_id in the value field - how do I concatenate all the boxes checked in order to put more than one category_id in the pf_survey category_ids field? Does this call for an array? Does it even make sense to do it like this? Thank you for any help. Duffy Betterton Director of Publications 615-277-3265 dbetterton@mtadistributors.com www.mtadistributors.com