Question

I am new to DB design and I am having some trouble finding info on how to define a “Many to One” relationship. I can find all sorts of info on “One to Many” and “Many to Many” but nothing on “Many to One”. My hangup is how to store the data. What I have is one table called “Categories” then I have another table called “Inventory”, each “Inventory” item can belong to multiple “Categories”.

How do I store multiple “Categories” in a single “Inventory” row? Should I have a intermediate table that stores the “Categories” ID with the corresponding “Inventory” ID? Or would adding something like a JSON string that has the “Categories” ID’s in the “Inventory” row be the right way to do this? Or is there a way to store an Array of “Categories” ID’s in the “Inventory” row?

Thanks allot for the help!

Answer 1

the correct term of Many to One is One to Many. simply create a table like this,

CREATE TABLE Categories
(
    CategoryID INT Primary KEY,
    CategoryName
);

CREATE TABLE InventoryList
(
    ProductID INT Primary KEY,
    CategoryID INT,
    ProductName VARCHAR(50),
    CONSTRAINT tb_fk FOREIGN KEY (CategoryID) REFERENCES Categories(CategoryID)
);