How to get the class name of all available subclasses

Question

Hi there!
Im developing an eComerce site as part of my studies this semester using JSP and mySQL. It's part of a bigger management system for a fictional company.
In the user interface, when adding new products to be available for sale on the website, I want the administrator to be able to choose what kind of product is being added. In the database I have the superclass[i] products with subclasses[i] harddrives, monitors etc.. The question is, can I somehow get the names of the subclasses constrained to a certain superclass? Maybe this question is more related to SQL querys than to JSP, but any help is appreciated:-)

Answer 1

First of all it is not conventional (or at least I find it very confusing) to call things as super class or sub class when referring to them in the database.
Why? because super class and sub class are really concepts in Object Oriented Programming languages, and probably (not sure) in Object Oriented Databases.
So I would call them main categories of products and sub categories of products.
And in databases I assume you have tables?
So say the table with main categories would have a primary key and a text field. The primary key is just like an index, and the text field holds the Main Category.
Similarly you would have another table representing sub categories.
But how would you associate a set of sub categories to each main category?
For this you would need a Foreign Key in the sub categories table.
The foreign key of a sub category maps to the primary key of the main category. Get it? If not you'll need to learn relational databases.
So if you know SQL you could write a SELECT statement in MySQL as follows:
SELECT product_category_name FROM product_sub_category psc, product_main_category psm WHERE psc.product_main_category = psm.product_main_category AND psm.product_main_category = 'Whatever Cagegory Name';
Message was edited by:
appy77