对商品进行数据库管理以存储其类别

Question

I have to create a web site witch contain goods. these goods have their own categories.for a example a good can be categorized in many categories or sub categories. I already have a item table witch contain their properties. and can anyone say how to keep it`s categories in database without duplicating data

Answer 1

Ok. In this case an Item may have many categories and a category may have many Items. So its a many to many relationship. Try as follows,

Your Item table may look like this,

Item( id , description, amount, ... )

In your Category table,

Category( id , name, description, ... )

And there will be another table to assign categories to items,

ItemCategoryAssignments( itemId , categoryId )

And there will be two foreign keys at ItemCategoryAssignments table. That,

itemId references id in the Item tabel

and

categoryId references id in the Category tabel

Like that. There will be no duplicated rows. Hope this will help.