DBMS Essentials: Organization, Integrity, and Access

Posted on Nov 18, 2024 in Computers

Database Management Systems (DBMS)

A DBMS is a software suite designed to access and manage databases. A database is a structured collection of related data.

Challenges of File Management

  • Data Redundancy and Inconsistency: Data duplication across various files and formats.
  • Physical-Logical Data Dependency: Changes in data structure require program modifications.
  • Difficulty in Data Access: Accessing data requires specific program code for each query.

Database Systems

A database is a large, organized store of related data, minimizing duplication and enabling simultaneous access by multiple users.

DBMS Functions

A DBMS allows users to create, define, and control access to a database. It provides:

  • Database creation and definition.
  • Data manipulation (insertion, updates, etc.).
  • Data access control and security mechanisms.
  • Data integrity and consistency checks.
  • Shared database access.
  • Backup and recovery mechanisms.

DBMS Components

DBMS Languages

Data Definition Language (DDL)

Used to specify the database schema, user views, and storage structures.

Data Manipulation Language (DML)

Used to read and update data in the database.

Data Security and Integrity

  • Ensures only authorized users access the database.
  • Detects constraint violations.
  • Provides backup mechanisms.
  • Enables database recovery to a consistent state.

DBMS Tools

Provides management tools for database administration, user management, and permissions.

Information Organization

  • Entity: A real-world object with identifiable characteristics.
  • Attribute: Characteristics of an entity.
  • Value: Data forming attributes.
  • Domain: Set of possible values for an attribute.

Keys

Attributes used to identify entity members.

  • Candidate Keys: Potential identifiers.
  • Primary Key: Chosen identifier.
  • Alternate Keys: Unchosen candidate keys.
  • Foreign Keys: Attributes serving as primary keys in other entities.

File Systems vs. DBMS

File systems manage individual files, while a DBMS manages interrelated files as a database.

Data Integrity

Ensures data accuracy and consistency, preventing duplication, deletion, and outdated data.

Data Redundancy

Repetition of data, minimized by DBMS.

Data Sharing

Allows multiple users to access the database with controlled permissions and concurrency management.

Relationship Types

  • Reflective: Entity relates to itself.
  • Binary: Relationship between two entities.
  • Ternary: Relationship between three entities.

Record Relationship Types

  • One-to-One (1:1): One record relates to one record in another entity.
  • One-to-Many (1:M): One record relates to many records in another entity.
  • Many-to-Many (M:M): Many records relate to many records in another entity.

DBMS Levels

  • Internal Level: Manages physical storage.
  • Logical Level: Controls data management.
  • External Level: User interface and views.

DBMS User Types

  • Computer Users: Administrators, programmers.
  • Non-Computer Users: General users with limited knowledge.

DBMS Types

  • Network DBMS
  • Hierarchical DBMS
  • Relational DBMS
  • Object-Oriented DBMS

Distribution Types

  • Centralized: All components on one machine.
  • Distributed: Components on multiple machines.