Neco 2025 Data Processing Question 5

Practice essay / theory question 5 from the 2025 Neco Data Processing examination. This question covers Database Management Systems .

Neco 2025 Data Processing Essay / Theory
Topic: Database Management Systems
Question 5 NECO • 2025 • DATA_PROCESSING • essay

A small retail store maintains information about its products, suppliers and purchase orders. The relational tables are defined as follows: - **Products**(ProductID, ProductName, UnitPrice, SupplierID) - **Suppliers**(SupplierID, SupplierName, ContactNo) - **PurchaseOrders**(OrderID, OrderDate, SupplierID) - **OrderDetails**(OrderID, ProductID, Quantity) Each product is supplied by exactly one supplier, a supplier may supply many products, each purchase order is placed with a single supplier, and an order can contain many different products. The store wishes to improve data integrity and automate some controls. Answer the following questions:

Question Parts

( a )
State the highest normal form (up to BCNF) that each of the four tables currently satisfies. Justify your answer for each table.
( b )
Write an SQL query that lists the names of suppliers who have supplied more than three **different** products in the last 30 days, assuming the current date is 2025‑06‑30. Show the logical steps you used to obtain the query.
( c )
The store wants to ensure that the total monetary value of each purchase order ( Σ UnitPrice × Quantity ) never exceeds ₦500,000. Propose a trigger (in pseudo‑SQL) that prevents the insertion of an OrderDetails row which would cause the total to go over this limit. Explain briefly how the trigger works.
( d )
Explain two possible consequences for the store if a transaction that updates OrderDetails violates the ACID properties.

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About This Question

This is Neco 2025 Data Processing Question 5. It is one of the essay questions from the 2025 Neco Data Processing examination.

The question covers Database Management Systems .

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