Database Systems – Exam 1
Complete Study Guide
Syllabus: Chapters 1, 2, 3 (except 3.8), 4 (except 4.6) from Elmasri &
Navathe, Fundamentals of Database Systems (7th Edition).
Chapter 1 – Databases and Database Users
- **Definition of Database**: A collection of related data representing some
aspect of the real world (mini-world).
- **DBMS**: Software to define, construct, manipulate, and share databases.
Functions: defining schema, querying, updating, backup, concurrency
control, security.
- **Database System** = Database + DBMS software.
- **Metadata**: Data about data (schemas, constraints) stored in catalog.
- **Main Characteristics**:
1. Self-describing (catalog with schema & constraints)
2. Program-data independence (data abstraction)
3. Multiple views of data (different subsets for different users)
4. Multi-user transaction processing (concurrency control, OLTP)
- **Advantages of DBMS**: controls redundancy, ensures consistency,
restricts unauthorized access, persistent storage, backup & recovery.
- **People around DBMS**:
- Actors on the scene: DBA, Designers, Users (casual, naïve, sophisticated,
standalone), Application programmers.
- Workers behind the scene: DBMS designers, tool developers, operators,
maintenance staff.
- **When Not to Use DBMS**: high overhead, simple one-user applications,
real-time constraints not met, very high initial cost.
Chapter 2 – Database System Concepts and
Architecture
- **Data Models**:
- High-level/Conceptual: ER, EER (easy for humans).
- Representational: Relational model (tables).
- Low-level/Physical: how data stored on disk.
- **Schemas vs Instances**:
