Normalize ShopDB to 3NF: extract Products and Warehouses tables

task.sql

@@ -1,33 +1,57 @@
 -- Create database and tables
 
+DROP DATABASE IF EXISTS ShopDB;
 CREATE DATABASE ShopDB;
 USE ShopDB;
 
+-- Table 1: Countries (unchanged)
 CREATE TABLE Countries (
-    ID INT,
-    Name VARCHAR(50),
+    ID   INT          NOT NULL,
+    Name VARCHAR(50)  NOT NULL,
     PRIMARY KEY (ID)
 );
 
-CREATE TABLE ProductInventory (
-    ID INT,
-    ProductName VARCHAR(50),
-    WarehouseAmount INT,
-    WarehouseName VARCHAR(50),
-    WarehouseAddress VARCHAR(50), 
+-- Table 2: Products (extracted from ProductInventory - 2NF/3NF: ProductName is not dependent on warehouse)
+CREATE TABLE Products (
+    ID   INT         NOT NULL,
+    Name VARCHAR(50) NOT NULL,
+    PRIMARY KEY (ID)
+);
+
+-- Table 3: Warehouses (extracted from ProductInventory - 3NF: warehouse info is not dependent on product)
+CREATE TABLE Warehouses (
+    ID        INT          NOT NULL,
+    Name      VARCHAR(50)  NOT NULL,
+    Address   VARCHAR(50)  NOT NULL,
     CountryID INT,
-	FOREIGN KEY (CountryID) REFERENCES Countries(ID) ON DELETE NO ACTION,
+    FOREIGN KEY (CountryID) REFERENCES Countries(ID) ON DELETE NO ACTION,
+    PRIMARY KEY (ID)
+);
+
+-- Table 4: ProductInventory (normalized - only 4 columns: ID, ProductID, WarehouseAmount, WarehouseID)
+CREATE TABLE ProductInventory (
+    ID              INT NOT NULL,
+    ProductID       INT NOT NULL,
+    WarehouseAmount INT NOT NULL,
+    WarehouseID     INT NOT NULL,
+    FOREIGN KEY (ProductID)   REFERENCES Products(ID)   ON DELETE NO ACTION,
+    FOREIGN KEY (WarehouseID) REFERENCES Warehouses(ID) ON DELETE NO ACTION,
     PRIMARY KEY (ID)
 );
 
 -- Populate test data
 
-INSERT INTO Countries (ID,Name)
-	VALUES (1, 'Country1');
-INSERT INTO Countries (ID,Name)
-	VALUES (2, 'Country2');
-
-INSERT INTO ProductInventory (ID,ProductName,WarehouseAmount,WarehouseName,WarehouseAddress,CountryID)
-	VALUES (1, 'AwersomeProduct', 2, 'Warehouse-1', 'City-1, Street-1',1);
-INSERT INTO ProductInventory (ID,ProductName,WarehouseAmount,WarehouseName,WarehouseAddress,CountryID)
-	VALUES (2, 'AwersomeProduct', 5, 'Warehouse-2', 'City-2, Street-2',2);
+INSERT INTO Countries (ID, Name) VALUES (1, 'Country1');
+INSERT INTO Countries (ID, Name) VALUES (2, 'Country2');
+
+INSERT INTO Products (ID, Name) VALUES (1, 'AwersomeProduct');
+
+INSERT INTO Warehouses (ID, Name, Address, CountryID)
+    VALUES (1, 'Warehouse-1', 'City-1, Street-1', 1);
+INSERT INTO Warehouses (ID, Name, Address, CountryID)
+    VALUES (2, 'Warehouse-2', 'City-2, Street-2', 2);
+
+INSERT INTO ProductInventory (ID, ProductID, WarehouseAmount, WarehouseID)
+    VALUES (1, 1, 2, 1);
+INSERT INTO ProductInventory (ID, ProductID, WarehouseAmount, WarehouseID)
+    VALUES (2, 1, 5, 2);