solution#109
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Review Summary
Excellent work on this task! Your task.sql script successfully meets all the requirements by correctly normalizing the database schema to the Third Normal Form (3NF).
You've done a fantastic job demonstrating a strong understanding of database design principles. Here are some of the highlights:
- Excellent Normalization: Creating separate
WarehousesandProductstables was the perfect approach. This correctly isolates distinct entities and eliminates the data redundancy and transitive dependencies found in the original structure. - Well-Designed Junction Table: The new
ProductInventorytable perfectly serves as a junction table, using foreign keys to efficiently link products to their stock in specific warehouses. - Correct Data Migration: The
INSERTstatements correctly populate the new tables, ensuring all the original data is preserved in the new, normalized structure.
This is a high-quality, professional solution. As a small suggestion for future projects, you could consider making your scripts idempotent (meaning they can be run multiple times without causing errors). You can do this by adding a DROP DATABASE IF EXISTS ShopDB; command at the top of your script.
DROP DATABASE IF EXISTS ShopDB;
CREATE DATABASE ShopDB;This is a common best practice that makes scripts easier to re-run during development and testing. It wasn't a requirement here, but it's a useful technique to know.
Overall, this is a fantastic submission. Keep up the great work
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Footnotes
| CREATE TABLE Warehouses( | ||
| ID INT, | ||
| Name VARCHAR(50), | ||
| Address VARCHAR(50), | ||
| CountryID INT, | ||
| FOREIGN KEY (CountryID) REFERENCES Countries(ID) ON DELETE NO ACTION, | ||
| PRIMARY KEY (ID) | ||
| ); |
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Excellent work creating a separate Warehouses table. This is a key step in normalization, as it isolates warehouse-specific attributes (Name, Address, CountryID) and eliminates data redundancy from the inventory table.
| CREATE TABLE Products( | ||
| ID INT, | ||
| Name VARCHAR(50), | ||
| PRIMARY KEY (ID) | ||
| ); |
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Perfect! Creating a Products table to store product-specific information (Name) is crucial for reaching the third normal form. This avoids data duplication and prevents potential update anomalies.
| 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, | ||
| ProductID INT, | ||
| FOREIGN KEY (ProductID) REFERENCES Products(ID) ON DELETE NO ACTION, | ||
| WarehouseID INT, | ||
| FOREIGN KEY (WarehouseID) REFERENCES Warehouses(ID) ON DELETE NO ACTION, | ||
| PRIMARY KEY (ID) | ||
| ); |
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This is a well-designed junction table. Using foreign keys ProductID and WarehouseID correctly links products to their stock in warehouses, achieving a normalized structure that is both efficient and consistent.
| 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); |
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These INSERT statements correctly populate the new Warehouses table, which is an essential part of migrating the data to the normalized schema.
| INSERT INTO Products (ID, Name) | ||
| VALUES (1, 'AwersomeProduct'); |
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This correctly populates the Products table with the product data, separating it from the inventory details as required by normalization.
| INSERT INTO ProductInventory (ID, WarehouseAmount, ProductID, WarehouseID) | ||
| VALUES (1, 2, 1, 1); | ||
| INSERT INTO ProductInventory (ID, WarehouseAmount, ProductID, WarehouseID) | ||
| VALUES (2, 5, 1, 2); |
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These statements correctly populate the ProductInventory linking table, associating the product with its stock count in each warehouse. This completes the data migration to the new 3NF structure. Well done!
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