Advice needed

I just want to seek some advice before I go further.

The scenario is like that. I have 2 tables.

1. Company
2. Product Category

One company can have one or more product category.

I have a form for product category. This form is just to add and maintain one field which is product category.

I have a form for company. This form is to key in company details like company name, address, phone etc and there is a button to save and go to next form. Next form is retrieve from Product Category table. And next to every product category there is a checkbox (view attachment - http://www.htmlforums.com/attachment.php?s=&postid=20182 9). My existing company got a field named productcategory. And when I save it, the productcategory field in Company table will have an appended value. Eg, 1,2,5,6 (assuming all these number is product category id).

My question is if let's say I ammend the product category either delete or modify it, this means there will no longer synchronize with productcategory field in company table.

So, I wonder in this situation what's the best solution. One company can have one or more product category and this product category is not fix.

Give companies a unique ID and

1) add a CompanyID field to the ProductCategory table, so every ProductCategory is linked to a Company

OR

2) Create another table that stores the CompanyID with a ProductCategoryID to associate ProductCategories with Copanies.

Use 1 if each product category is associated with only one company. Use 2 if a product category can be associated with more than one company.