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Normalize the database ShopDB #159

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Normalize the database ShopDB #159

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20f3551
Normalize the database ShopDB
AndS9 Mar 28, 2026
d2911d1
Fixes 1.0.1
AndS9 Mar 28, 2026
faf9a90
Fixes 1.0.2
AndS9 Mar 28, 2026
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27 changes: 18 additions & 9 deletions task.sql
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Original file line number Diff line number Diff line change
Expand Up @@ -9,14 +9,20 @@ CREATE TABLE Countries (
PRIMARY KEY (ID)
);

CREATE TABLE Warehouses (
ID INT,
Name VARCHAR(50),
Address VARCHAR(100),
CountryID INT,
FOREIGN KEY (CountryID) REFERENCES Countries(ID) ON DELETE NO ACTION,
PRIMARY KEY (ID)
);
CREATE TABLE ProductInventory (
ID INT,
ProductName VARCHAR(50),
WarehouseAmount INT,
WarehouseName VARCHAR(50),
WarehouseAddress VARCHAR(50),
CountryID INT,
FOREIGN KEY (CountryID) REFERENCES Countries(ID) ON DELETE NO ACTION,
WarehouseID INT,
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@mateacademy-ai-mentor mateacademy-ai-mentor Mar 28, 2026

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While this table might seem to be in 3NF with ID as the primary key, it doesn't fully meet the goals of normalization. The ProductName column creates data redundancy (e.g., 'AwesomeProduct' is repeated), which can lead to update, insertion, and deletion anomalies. A better 3NF design would involve creating a separate Products table for product information and using a ProductID foreign key in this table instead of ProductName.

FOREIGN KEY (WarehouseID) REFERENCES Warehouses(ID) ON DELETE CASCADE,
PRIMARY KEY (ID)
);

Expand All @@ -26,8 +32,11 @@ 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 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,ProductName,WarehouseAmount,WarehouseID)
VALUES (1, 'AwesomeProduct', 2, 1);
INSERT INTO ProductInventory(ID,ProductName,WarehouseAmount,WarehouseID)
VALUES (2, 'AwesomeProduct', 5,2);
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