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Normalize ShopDB to 3NF: extract Products and Warehouses tables #157

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Normalize ShopDB to 3NF: extract Products and Warehouses tables #157

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Normalize ShopDB to 3NF: extract Products and Warehouses tables
NazarKulyk6 Mar 19, 2026
6103359
Fix: add DROP DATABASE IF EXISTS, set ProductID and WarehouseID as NO…
NazarKulyk6 Mar 19, 2026
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59 changes: 41 additions & 18 deletions task.sql
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Original file line number Diff line number Diff line change
Expand Up @@ -3,31 +3,54 @@
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,
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@mateacademy-ai-mentor mateacademy-ai-mentor Mar 19, 2026

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Good job creating the ProductInventory table. However, consider making ProductID NOT NULL. An inventory record wouldn't make sense if it wasn't associated with a specific product. This change will improve the data integrity of your table.

WarehouseAmount INT NOT NULL,
WarehouseID INT,
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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);
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