Database Approach

2.1 Database Approach

Suggested retrieval lesson: 20–30 minutes.

Recall first

1. What problem does a database approach solve that separate files do not?
2. Distinguish a database from a DBMS.
3. What do primary key, foreign key, and data integrity mean?

Answer before reading.

From files to a managed database

In a traditional file-processing approach, each application keeps its own files. The same customer may be stored separately by sales, support, and finance. This creates duplication, inconsistent updates, difficult sharing, weak security, and strong dependence between programs and file formats. The database approach stores related organizational data in a shared, managed collection and lets authorized applications/users access it through a database management system (DBMS). IBM defines a database as an organized digital repository and explains that database systems support storage, management, and access. IBM, “What is a database?”

A database is the data and its logical organization. A DBMS is the software that defines, stores, queries, updates, secures, and administers that data. A database system also includes people, procedures, applications, and hardware. Do not write “database = DBMS” in an exam.

Relational foundations

In a relational database, a table/relation contains rows (records/tuples) and columns (attributes/fields). A primary key uniquely identifies each row. A foreign key stores a key from another table to represent a relationship. For example:

• Customer(CustomerID, Name)
• Order(OrderID, CustomerID, OrderDate)
• OrderLine(OrderID, ProductID, Quantity)

One customer can have many orders; an order can have many products, represented safely through OrderLine. A schema describes structure, constraints, and relationships; SQL is a common language for querying and changing relational data.

Quality and control

The database approach reduces unnecessary redundancy but does not magically make data correct. Entity integrity requires a valid unique primary key; referential integrity prevents an order referring to a non-existent customer. Validation rules, access permissions, audit logs, backup, and transaction controls protect quality and security.

A transaction is a logical unit of work. The familiar ACID properties are: atomicity (all or none), consistency (rules remain valid), isolation (concurrent transactions do not improperly interfere), and durability (committed work survives failure). These are useful supplements for explaining why a banking transfer must not debit one account without crediting the other; exact DBMS guarantees depend on configuration.

Worked example: duplicate customers

A spreadsheet system has SalesCustomer and SupportCustomer. A customer changes address, but only sales updates it. Reports disagree. A database redesign creates one CustomerID, a single customer record, and foreign-key references from sales and support. The database reduces update anomaly risk, while a DBMS enforces constraints and permissions. It still needs a data-governance rule for who may change an address and a process for merging historical duplicates.

Exercise — reveal after committing

An OrderLine row contains OrderID = 81, but no order 81 exists. Which concept is violated, and what control prevents it? Why is a primary key alone insufficient?

Revealed answer: Referential integrity is violated; a foreign-key constraint can reject the orphan row. A primary key only ensures uniqueness within OrderLine; it does not prove that the referenced parent order exists.

Exam lens

• Database vs DBMS: organized data vs software that manages it.
• Database approach vs file approach: shared controlled data, reduced redundancy, integrity, security, and data independence versus isolated duplication and inconsistency.
• Primary key vs foreign key: identifies a row vs connects to a row in another table.
• State trade-offs: DBMSs add cost, administration, complexity, and a concentration-of-failure risk; the benefits are controlled sharing and consistency.

Rapid revision checklist

• Explain three file-processing problems.
• Define database, DBMS, schema, table, record, field.
• Use primary and foreign keys in a small example.
• Explain entity and referential integrity.
• State ACID and its relevance to transactions.

Key takeaways

1. The database approach treats data as a shared organizational resource.
2. A DBMS manages access, constraints, queries, updates, and recovery.
3. Keys and integrity rules preserve meaningful relationships.
4. Centralization improves consistency but requires governance, security, and administration.

Sources

• Rainer & Prince, Management Information Systems (Wiley) — textbook exam framing for database approach and DBMS.
• Laudon & Laudon, Management Information Systems: Managing the Digital Firm, 10th ed. — textbook exam framing for data organization and database management.
• Boddy & Boonstra, Managing Information Systems: Strategy and Organization — textbook exam framing.
• IBM, “What is a database?” — supplement for database concepts and uses.
• Oracle, Database Concepts — supplement for relational database and transaction concepts.