Solution

task.sql

@@ -1,33 +1,49 @@
--- Create database and tables
+-- Create database and tables (normalized to 3NF)
 
+DROP DATABASE IF EXISTS ShopDB;
 CREATE DATABASE ShopDB;
 USE ShopDB;
 
 CREATE TABLE Countries (
-    ID INT,
-    Name VARCHAR(50),
-    PRIMARY KEY (ID)
+    ID INT PRIMARY KEY,
+    Name VARCHAR(50) NOT NULL
 );
 
-CREATE TABLE ProductInventory (
-    ID INT,
-    ProductName VARCHAR(50),
-    WarehouseAmount INT,
-    WarehouseName VARCHAR(50),
-    WarehouseAddress VARCHAR(50), 
+CREATE TABLE Products (
+    ID INT PRIMARY KEY,
+    Name VARCHAR(100) NOT NULL
+);
+
+CREATE TABLE Warehouses (
+    ID INT PRIMARY KEY,
+    Name VARCHAR(100) NOT NULL,
+    Address VARCHAR(200),
     CountryID INT,
-	FOREIGN KEY (CountryID) REFERENCES Countries(ID) ON DELETE NO ACTION,
-    PRIMARY KEY (ID)
+    FOREIGN KEY (CountryID) REFERENCES Countries(ID) ON DELETE NO ACTION
+);
+
+CREATE TABLE ProductInventory (
+    ID INT PRIMARY KEY,
+    ProductID INT NOT NULL,
+    WarehouseID INT NOT NULL,
+    WarehouseAmount INT NOT NULL,
+    FOREIGN KEY (ProductID) REFERENCES Products(ID) ON DELETE CASCADE,
+    FOREIGN KEY (WarehouseID) REFERENCES Warehouses(ID) ON DELETE CASCADE
 );
 
--- 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);
+-- Populate test data adjusted for normalized schema
+
+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,WarehouseID,WarehouseAmount)
+    VALUES (1, 1, 1, 2);
+INSERT INTO ProductInventory (ID,ProductID,WarehouseID,WarehouseAmount)
+    VALUES (2, 1, 2, 5);