Database Management Systems: A Comprehensive Guide
Database Management Systems
Introduction
Data storage requires defining two key features: Logical Design (user-level design, how users view and manage data) and Physical Design (implementation-level design, how data is stored on disks). Two primary types of physical design exist: data files and databases.
Database Concepts
Database (DB)
A collection or integrated data warehouse stored on secondary storage with controlled redundancy. Data should remain independent of applications and support a data model that captures real-world interrelationships and restrictions.
Database Management System (DBMS)
A set of programs that enable the implementation, access, and maintenance of a database. Along with the database and users, these components form the database system.
Benefits of DBMS
Data Benefits
- Independence from applications in terms of data handling.
- Improved data availability.
- Increased efficiency in data collection, coding, and entry.
Result Benefits
- Enhanced data consistency.
- More informative outputs.
- Better and more standardized documentation.
User Benefits
- Faster and easier data access for end-users.
- Simplified data sharing among users.
- Increased flexibility in meeting evolving demands.
Types of Database Systems
Relational databases efficiently manage formatted data with a moderate level of security. Emerging applications require support for more sophisticated data types, handling the temporal dimension, enhanced security, and managing imprecise data.
Database Security
Data Integrity
Protecting the database from operations that introduce inconsistencies in the data. Integrity refers to the correctness, validity, or accuracy of the data within a database.
Data Availability
Ensuring data accessibility to authorized users by providing mechanisms to recover the database from logical or physical failures that may destroy data partially or entirely. Maintaining a consistent database state is crucial. This involves creating execution units called transactions (a sequence of operations that must be executed atomically), ensuring that either all operations within a transaction are performed or none are.
Data Confidentiality
The system must identify and authenticate users. The data manager or owner must specify the privileges granted to authorized users for accessing database objects.