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ITM 203

Database Management System

TU BITM · Semester 3 · BITM curriculum and programme regulation

Requirement
required
Credits
3
Study Guide
7 units available

Chapter notes

Authoritative study guide across 7 syllabus units

Open a unit to read its study notes.

Unit 1: Database Concepts and Architecture· 4 LHs· ~5 marks

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Part 1: Core Concepts (2 Marks)

  • DBMS (Database Management System): A computerized software suite that enables users to define, construct, manipulate, and share electronic databases among various applications and users.
  • Three-Schema Architecture (ANSI/SPARC): Separates user views from the physical database: External Level (user views) →\to Conceptual Level (logical schema) →\to Internal Level (physical storage structures).
  • Data Independence:
    • Logical Data Independence: Capacity to modify the conceptual schema without altering external schemas or application programs.
    • Physical Data Independence: Capacity to modify the internal schema (storage devices, indexes, hash structures) without altering the conceptual schema.

Part 2: Structural Frameworks (10 Marks)

ANSI/SPARC Three-Schema Architecture

  1. | View 1 (Student View) View 2 (Accountant View) View 3 ... | <-- External Level
  2. External/Conceptual Mapping
    • | Conceptual Schema (Entities, Relationships, Constraints) | <-- Conceptual Level
  3. Conceptual/Internal Mapping
    • | Internal Schema (B-Trees, Hashing, File Storage Blocks) | <-- Internal Level
    • [Physical Database on Disk/SSD]

Part 3: Distinction Tables

Basis of Comparison Traditional File Processing System Database Management System (DBMS)
Data Redundancy High duplication across separate program files. Controlled and minimized redundancy via central normalization.
Data Consistency Low; updating one file leaves duplicates outdated. High; ACID properties guarantee uniform system-wide updates.
Data Access Hardcoded custom access programs needed for each query. Standard declarative query language (SQL).
Concurrent Access Poor; file-locking causes severe concurrency bottlenecks. Granular multi-version concurrency control (MVCC) and locking.

Part 4: Worked Problems & Exam Traps

Database Administrator (DBA) Core Roles

The DBA is responsible for:

  1. Schema definition and physical storage organization.
  2. Granting authorization and access rights for database security.
  3. Routine monitoring of system performance and database tuning.
  4. Implementing automated backup and disaster recovery procedures.

Do not confuse schema with instance! Schema is the static structure/skeleton defined in DDL; instance is the actual collection of data records populated in the database at a specific point in time.