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Solved #127

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NizArtem Nov 4, 2025
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NizArtem Nov 4, 2025
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NizArtem Nov 4, 2025
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NizArtem Nov 4, 2025
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28 changes: 20 additions & 8 deletions task.sql
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Original file line number Diff line number Diff line change
Expand Up @@ -9,14 +9,21 @@ CREATE TABLE Countries (
PRIMARY KEY (ID)
);

CREATE TABLE Warehouse (
ID INT,
Name VARCHAR(50),
CountryID INT,
Address VARCHAR(50),
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,
FOREIGN KEY (WarehouseID) REFERENCES Warehouse(ID) ON DELETE NO ACTION,
PRIMARY KEY (ID)
);
Comment on lines 21 to 28

@mateacademy-ai-mentor mateacademy-ai-mentor Nov 4, 2025

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Because CountryID is determined by the WarehouseID, keeping CountryID in this table creates a transitive dependency (ProductInventory.ID -> WarehouseID -> CountryID). To adhere to 3NF, the CountryID column and its foreign key constraint should be removed from this table and placed in the Warehouse table instead.


Expand All @@ -26,8 +33,13 @@ INSERT INTO Countries (ID,Name)
VALUES (1, 'Country1');
INSERT INTO Countries (ID,Name)
VALUES (2, 'Country2');

INSERT INTO Warehouse (ID, Name, CountryID, Address)
VALUES (1, 'Warehouse-1', 1, 'City-1, Street-1');
INSERT INTO Warehouse (ID, Name, CountryID, Address)
VALUES (2, 'Warehouse-2', 2, 'City-2, Street-2');

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 ProductInventory (ID,ProductName,WarehouseAmount,WarehouseID)
VALUES (1, 'AwersomeProduct', 2, 1);
INSERT INTO ProductInventory (ID,ProductName,WarehouseAmount,WarehouseID)
VALUES (2, 'AwersomeProduct', 5, 2);
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