Part 1 — Database Concepts & Characteristics
CLO1 · 20 marks. The warm-up — the easiest marks to bank if your definitions are crisp and you nail the user → role table. Don't lose them to vagueness.
Q1smallDefine Database (DB) and DBMS. Give an example of a relational, NoSQL and cloud database system. (1 + 1)
Q2Map each DB user to their role(s). One is solved: (4) = (a). (3 marks)
Supporting theory (likely short-answer fodder)
DBMS vs. file processing — the 6 drawbacks of files
RI·IACSRedundancy/inconsistency · Isolation · Integrity · Atomicity · Concurrency anomalies · Security.
A DBMS fixes all six: single source of truth, unified access, enforced constraints, transactions, concurrency control, and granular security.
Three levels of data abstraction
| Level | Also called | What it describes | Who works here |
|---|---|---|---|
| Physical | Internal | How data is stored (structures, indexing) | DBA |
| Logical | Conceptual | What data + relationships | Designers / programmers |
| View | External | Per-user slices of the data | End users |
Data independence: changing a lower level without disturbing the one above it — physical independence (storage changes don't affect the logical schema) and logical independence (logical changes don't affect views).
DBMS architectures
| Architecture | Idea | Typical use |
|---|---|---|
| Centralized | One server, all storage + processing | Small, single-branch institutions |
| Client-Server | Clients = UI, server = data (2/3-tier) | Banking, university, enterprise apps |
| Distributed | Data across sites (fragmentation + replication) | Multinationals, cloud systems |
| Parallel | Parallel query execution (shared-memory / -disk / -nothing) | Data warehousing, big-data analytics |