如何将一个表的自动生成的ID插入另一表的ID

Question

I am trying to make a project which is an Online shopping website. I have three tables,namely, Category Table, Sub-Category Table and Products table. In category table I have CategoryID and CategoryName as the two fileds.In Sub-Category table I have CategoryID , Sub-CategoryID and SubCategoryName as the fields, and in products table I have CategoryID , SubCategoryID , ProductID and ProductName .

Now in category table , the categoryID is autogenerated and set as primary key.In sub-Category table, the none of the keys are auto generated and both the categoryID and subCategory ID are set to combined primary keys. Now ,when I insert a categoryName into the category table, I want the CategoryID(auto-generated) to be inserted in the categoryID column of the SubCategory table and the CategoryID column of the ProductTable. There is a lot of content in the net on this matter, but none solves exactly my problem.

Answer 1

I feel there is a bad smell in your design.

You do not need to have a composite primary key in your sub tables since you already have a unique identifier defined in your table. Instead, just use one column as a primary key and add foreign key relations to your sub tables.

Answer 2

I think You shud user SCOPE_IDENTITY for that

SCOPE_IDENTITY returns the last identity value generated for any table.

Answer 3

INSERT INTO Category (....) VALUES(....)

DECLARE @id int;
SELECT @id=SCOPE_IDENTITY();

INSERT INTO Subcategory(CatagoryID,....) VALUES(@id,....)
INSERT INTO Product (CategoryID,....) Values(@id,...)