MySQL: how to do row-level security (like Oracle's Virtual Private Database)?

Question

Say that I have vendors selling various products. So, at a basic level, I will have the following tables: vendor, product, vendor_product

Answer 1

This sounds to me that you want to normalize your data. What you have is a 1 (product) to many (vendors) relationship. That the relationship is 1:1 for most cases and only 1:n for some doesn't really matter I would say - in general terms it's still 1:n and therefor you should design your database this way. The basic layout would probably be this:

Vendor Table
VendorId    VendorName    OtherVendorRelatedInformation

WidgetTable
WidgetId    WidgetName    WidgetFlag     CreatorVendor   OtherWidgetInformation

WidgetOwnerships
VendorId    WidgetId      OwnershipStatus     OtherInformation

Update: The question of who is allowed to do what is a business problem so you need to have all the rules laid out. In the above structure you can flag which vendor created the widget. And in the ownership you can flag what the status of the ownership is, for example

• CreatorFullOwnership
• SharedOwnership
• ...

You would have to make up the flags based on your business rules and then design the business logic and data access part accordingly.