solution#120
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Review Summary
Decision: REQUEST_CHANGES — a few missing constraints and engine settings are critical to data integrity and can cause test failures.
Why: Your schema meets the 3NF decomposition and inserts are correct, but several required constraints and settings are missing. These are critical blockers because they violate explicit checklist items (NOT NULL/UNIQUE, non-negative quantity) and can break referential integrity if the storage engine doesn’t enforce FKs.
Critical issues to fix (with where/why/how):
- Countries.Name and Products.Name not enforced as unique/non-null (task.sql — CREATE TABLE for Countries, Products)
- Why: Checklist 2.6/3.2 requires unique identifiers; NULLs/duplicates break integrity and tests.
- How: Set
NametoVARCHAR(50) NOT NULL UNIQUEin both tables.
- Missing NOT NULL on FK and key columns (task.sql — Warehouses.CountryID; Inventory.ProductID, Inventory.WarehouseID)
- Why: Checklist 3.4 expects NOT NULL on required references; NULL breaks referential semantics.
- How: Declare these columns
NOT NULL.
- Inventory quantity allows NULL/negative values (task.sql — Inventory.WarehouseAmount)
- Why: Checklist 3.3/3.4 requires non-negative, non-null quantities.
- How: Change to
WarehouseAmount INT UNSIGNED NOT NULL(or an appropriate unsigned numeric type).
- Engine not specified for FK enforcement (all CREATE TABLE statements)
- Why: MySQL enforces FKs only with InnoDB; without it, constraints may be ignored on some servers (Checklist 2.4).
- How: Add
ENGINE=InnoDB(optionallyDEFAULT CHARSET=utf8mb4).
Important but non-blocking improvements:
- IDs as surrogate keys with auto-increment (Countries/Products/Warehouses): use
INT AUTO_INCREMENT PRIMARY KEY(Checklist 3.3). If you switch, remove explicit IDs from INSERTs or adjust accordingly. - Consider explicit FK actions: e.g.,
ON DELETE RESTRICT ON UPDATE CASCADEfor clarity (Checklist 2.4). - Warehouses: make
NameandAddressNOT NULL; considerUNIQUE(Name)orUNIQUE(Name, Address)depending on intended uniqueness (Checklist 3.2). - Decide on
DROP DATABASE IF EXISTS ShopDB;vs the exactDROP DATABASE ShopDB;if your grader requires the literal statement. The current form is safer and idempotent. - Minor: fix product name typo
AwersomeProduct→AwesomeProductif unintended.
You’re very close — the design is solid. Add these constraints/engine settings and you should fully meet the requirements. Keep it up!
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Footnotes
| -- Create database and tables | ||
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| -- 🔄 Пересоздаємо базу | ||
| DROP DATABASE IF EXISTS ShopDB; |
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Line uses DROP DATABASE IF EXISTS which is idempotent and safer. The task description mentioned dropping ShopDB before creation (the spec used DROP DATABASE ShopDB;). If your grader expects the exact statement, change to DROP DATABASE ShopDB;. Otherwise, keeping IF EXISTS is preferable because it avoids an error when the DB does not exist (and still satisfies the intent of removing any pre-existing DB).
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Countries table: ID INT PRIMARY KEY is valid but the checklist recommends surrogate keys (INT AUTO_INCREMENT) for IDs (3.3). Also add constraints on the name column: Name should be NOT NULL and UNIQUE to satisfy requirement 2.6 / 3.2 (unique country names). Consider changing to ID INT AUTO_INCREMENT PRIMARY KEY and Name VARCHAR(50) NOT NULL UNIQUE.
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Products table: The ID column is currently INT PRIMARY KEY — consider INT AUTO_INCREMENT PRIMARY KEY for a surrogate key (requirement 3.3). Also make Name NOT NULL and UNIQUE (Products.Name should be unique in test data per 3.2). This enforces data integrity and matches checklist constraints (2.3, 3.2).
| Address VARCHAR(100), | ||
| CountryID INT, | ||
| FOREIGN KEY (CountryID) REFERENCES Countries(ID) ON DELETE NO ACTION | ||
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Warehouses table: Add stronger constraints: ID can be INT AUTO_INCREMENT PRIMARY KEY; Name and Address should be NOT NULL. Also make CountryID NOT NULL and consider adding a uniqueness constraint — either UNIQUE(Name) if names are unique, or UNIQUE(Name, Address) to handle same-name warehouses in different places (check checklist 3.2). Finally, ensure the CREATE TABLE uses ENGINE=InnoDB so the FK to Countries is enforced (requirement 2.4).
| WarehouseID INT, | ||
| WarehouseAmount INT, | ||
| WarehouseName VARCHAR(50), | ||
| WarehouseAddress VARCHAR(50), | ||
| CountryID INT, | ||
| FOREIGN KEY (CountryID) REFERENCES Countries(ID) ON DELETE NO ACTION, | ||
| PRIMARY KEY (ID) | ||
| PRIMARY KEY (ProductID, WarehouseID), | ||
| FOREIGN KEY (ProductID) REFERENCES Products(ID), | ||
| FOREIGN KEY (WarehouseID) REFERENCES Warehouses(ID) | ||
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Inventory table (junction): Good that you modeled amount via a junction table with a composite PK (ProductID, WarehouseID). Improvements needed: make ProductID and WarehouseID NOT NULL; ensure the quantity column is non-negative and NOT NULL (e.g., WarehouseAmount INT UNSIGNED NOT NULL), per checklist 3.3/3.4. Also add ENGINE=InnoDB to ensure FK enforcement and consider explicit ON DELETE/ON UPDATE behavior for your FKs (e.g., ON DELETE RESTRICT or ON DELETE CASCADE depending on desired semantics).
| (2, 'Country2'); | ||
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| -- Продукт | ||
| INSERT INTO Products (ID, Name) VALUES | ||
| (1, 'AwersomeProduct'); | ||
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| -- Склади |
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INSERTs and test data: Insert order (countries → products → warehouses → inventory) is correct and IDs line up. Note: if you change ID columns to AUTO_INCREMENT, either remove explicit ID values from INSERTs or explicitly set SET SESSION sql_mode = 'NO_AUTO_VALUE_ON_ZERO' / use INSERT with IDs intentionally. Also I noticed the product name AwersomeProduct — if that was meant to be AwesomeProduct, fix the spelling to preserve intended semantics.
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Review Summary
Main decision: Requesting changes because a few checklist-required names/statements are not met and will likely cause grading failures.
Critical issues to fix (blockers):
- Line ~2: DROP statement uses
DROP DATABASE IF EXISTS ShopDB;. The checklist item 1.2 calls for the literalDROP DATABASE ShopDB;. If your grader is strict about exact text, replace it. Why: strict graders may search for that exact string. How: change toDROP DATABASE ShopDB;. - Line ~18 (CREATE TABLE Products): Column is
Name VARCHAR(50) NOT NULL UNIQUE. Requirement (3.1/3.2/4.3) isProductName. Why: tests expect exact column names. How: rename toProductName VARCHAR(50) NOT NULL UNIQUEand update every reference:- INSERT INTO Products: change column list from
(ID, Name)to(ID, ProductName). - Any JOINs/VIEW: replace
p.Namewithp.ProductName.
- INSERT INTO Products: change column list from
- Line ~39 (CREATE TABLE Inventory): Column is
WarehouseAmount INT UNSIGNED NOT NULL. Requirement (3.1/3.2/4.3) isQuantity. Why: tests check forQuantity. How: rename toQuantity INT UNSIGNED NOT NULLand update references:- INSERT INTO Inventory: use
(ProductID, WarehouseID, Quantity); values stay numerically the same. - VIEW: replace
i.WarehouseAmountwithi.Quantity.
- INSERT INTO Inventory: use
Minor/clarifying tips:
- After renaming columns, ensure the compatibility VIEW selects
p.ProductNameandi.Quantity. If the old consumer expects the legacy column names, you can alias as needed (e.g.,i.Quantity AS WarehouseAmount) while keeping the internal schema correct. - Re-run the script end-to-end to catch any lingering references.
What you did well:
- Strong 3NF design with proper PKs/FKs, InnoDB, unsigned quantities, and a helpful compatibility VIEW. Creation order and test data mapping look solid.
Once these naming and literal DROP fixes are applied, the submission should pass the checklist and function as intended. Keep it up!
✨ Please rate this review in the Platform's notification center1. I will be grateful for your feedback! ✨
Important
Fix the issues, commit the changes, and then re-request my review using the Re-request review button2 in the Reviewers tab.
Tip
If you have any comments about this review, please leave a message in the Add a comment section below and mention me with the @mateacademy-ai-mentor tag3.
I will read your message during my next review of your pull request. Please do not reply directly to my comments, as that feature is not supported yet.
Caution
Do not close the pull request until the review is complete. Closing it early can lead to unexpected behavior and disrupt the review process.
Footnotes
| -- Create database and tables | ||
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| -- 1. Пересоздаємо базу | ||
| DROP DATABASE IF EXISTS ShopDB; |
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Potential strict-grader issue: You use DROP DATABASE IF EXISTS ShopDB;. The checklist item 1.2 explicitly requires dropping ShopDB using the literal DROP DATABASE ShopDB; (without IF EXISTS). If the grader expects the exact statement, please replace this line with DROP DATABASE ShopDB;. If the grader accepts IF EXISTS as equivalent, no change is needed. (Checklist reference: 1.2 / 4.4)
| CREATE TABLE Products ( | ||
| ID INT NOT NULL AUTO_INCREMENT, | ||
| Name VARCHAR(50) NOT NULL UNIQUE, | ||
| PRIMARY KEY (ID) |
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The Products table currently declares the column as Name VARCHAR(50) NOT NULL UNIQUE. The checklist requires the Products table to use the column name ProductName. Please rename to ProductName VARCHAR(50) NOT NULL UNIQUE and update all references (INSERT INTO Products, the VIEW, and any JOINs) accordingly. (Checklist references: 3.1, 3.2, 4.3)
| (1, 'AwersomeProduct'); | ||
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INSERT into Products currently uses (ID, Name) — after renaming the Products column you must update this INSERT to (ID, ProductName) and set the VALUES accordingly. Ensure the inserted product continues to match the original dataset. (Checklist references: 1.6, 3.5)
| ProductID INT NOT NULL, | ||
| WarehouseID INT NOT NULL, | ||
| WarehouseAmount INT UNSIGNED NOT NULL, | ||
| PRIMARY KEY (ProductID, WarehouseID), |
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Inventory column is named WarehouseAmount INT UNSIGNED NOT NULL. The checklist requires the association table column to be named Quantity (not WarehouseAmount). Please rename to Quantity INT UNSIGNED NOT NULL and update all INSERTs and the VIEW to use Quantity. (Checklist references: 3.1, 3.2, 4.3)
| (1, 1, 2), | ||
| (1, 2, 5); | ||
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INSERT statements into Inventory currently list values for WarehouseAmount. Update the INSERT column list to (ProductID, WarehouseID, Quantity) and change the VALUES to match (the numeric values stay the same). Example: (1, 1, 2) remains but must be inserted into Quantity. (Checklist references: 1.6, 3.5)
| i.WarehouseAmount, | ||
| w.Name AS WarehouseName, |
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The VIEW selects p.Name AS ProductName and i.WarehouseAmount. After renaming Products.Name → ProductName and Inventory.WarehouseAmount → Quantity, update the view to use p.ProductName and i.Quantity. This keeps backward compatibility while using the normalized column names internally. (Checklist reference: 1.6 / compatibility view)
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Review Summary
Educational approval: You’re on the right track with a solid 3NF schema, correct FK relationships, non-negative Quantity via INT UNSIGNED, proper DDL/DML ordering, and a helpful compatibility VIEW. Nice work aligning the schema to the checklist core items and keeping it MySQL-executable end-to-end.
Critical issues to address next:
- Checklist 3.3 (uniqueness for warehouses): In
task.sql, insideCREATE TABLE Warehouses(around the table definition block), there’s no UNIQUE constraint on warehouse identity. Without this, duplicates can slip in. Consider adding one of:UNIQUE (Name)if names are globally unique, orUNIQUE (Name, Address)if uniqueness is defined by the combination. This prevents update anomalies and should satisfy automated checks. - Data consistency: On or near line 58, the product name
AwersomeProductappears misspelled. If tests expect the original value (likelyAwesomeProduct), update the INSERT to match exactly to avoid mismatches.
Minor improvements (recommended):
- Checklist 4.3: Name your constraints explicitly for clarity and verifiability, e.g.,
CONSTRAINT pk_countries PRIMARY KEY (ID),CONSTRAINT pk_products PRIMARY KEY (ID),CONSTRAINT pk_warehouses PRIMARY KEY (ID),CONSTRAINT pk_inventory PRIMARY KEY (ProductID, WarehouseID).
You’ve done the heavy lifting well—just tighten the warehouse uniqueness and verify the product name spelling. Keep going; you’re very close to a fully compliant and robust submission!
✨ Please rate this review in the Platform's notification center1. I will be grateful for your feedback! ✨
Footnotes
| -- 2.3 Warehouses | ||
| CREATE TABLE Warehouses ( | ||
| ID INT NOT NULL AUTO_INCREMENT, | ||
| Name VARCHAR(50) NOT NULL, |
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The Name column for Warehouses is defined but there is no UNIQUE constraint. Checklist item 3.3 requires warehouse identity be uniquely defined to prevent duplicates/update anomalies. Add a uniqueness constraint — either on Name alone or as a composite with Address.
Example options to add inside the CREATE TABLE block:
UNIQUE KEY uq_warehouses_name (Name),-- if warehouse name alone is uniqueUNIQUE KEY uq_warehouses_name_addr (Name, Address),-- if name+address defines uniqueness
Pick the option that matches your domain expectations and update the table DDL accordingly.
| ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4; | ||
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| -- 2.2 Products | ||
| CREATE TABLE Products ( | ||
| ID INT NOT NULL AUTO_INCREMENT, | ||
| ProductName VARCHAR(50) NOT NULL UNIQUE, | ||
| PRIMARY KEY (ID) | ||
| ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4; | ||
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| -- 2.3 Warehouses | ||
| CREATE TABLE Warehouses ( | ||
| ID INT NOT NULL AUTO_INCREMENT, | ||
| Name VARCHAR(50) NOT NULL, | ||
| Address VARCHAR(100) NOT NULL, | ||
| CountryID INT NOT NULL, | ||
| PRIMARY KEY (ID), | ||
| CONSTRAINT fk_warehouses_country | ||
| FOREIGN KEY (CountryID) REFERENCES Countries(ID) | ||
| ON DELETE RESTRICT | ||
| ON UPDATE CASCADE | ||
| ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4; | ||
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| -- 2.4 Inventory | ||
| CREATE TABLE Inventory ( | ||
| ProductID INT NOT NULL, | ||
| WarehouseID INT NOT NULL, | ||
| Quantity INT UNSIGNED NOT NULL, | ||
| PRIMARY KEY (ProductID, WarehouseID), | ||
| CONSTRAINT fk_inventory_product |
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Primary keys are present but are not named with explicit constraint identifiers. Checklist item 4.3 recommends explicitly naming primary keys (where possible) to improve verifiability. Consider changing the anonymous PRIMARY KEY declarations to named constraints, for example:
CONSTRAINT pk_countries PRIMARY KEY (ID)CONSTRAINT pk_products PRIMARY KEY (ID)CONSTRAINT pk_warehouses PRIMARY KEY (ID)CONSTRAINT pk_inventory PRIMARY KEY (ProductID, WarehouseID)
This is not required for execution but makes automated checks and reviews clearer.
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| INSERT INTO Products (ID, ProductName) VALUES | ||
| (1, 'AwersomeProduct'); | ||
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Double-check the product name inserted here: AwersomeProduct. The checklist requires that the test data reconstruct the same logical dataset as the original ProductInventory. If the original name was AwesomeProduct (or another spelling), update this value to match the original to avoid test mismatches.
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