Database Management Systems Quiz

Study Notes

A DBMS is a software system that provides tools for managing and accessing data.
The collection of data managed by a DBMS is called a database.
Key goals of a DBMS are convenient and efficient data storage and retrieval.
DBMS are designed to manage large amounts of data, including defining data structures, providing data manipulation mechanisms, and ensuring data safety.

Enterprise Information Management: This involves managing information within organizations to make informed decisions.
Banking and Finance: Used for managing accounts, transactions, and other financial data.
Universities: For managing student information, course registration, and other academic operations.
Airlines: Used for booking flights, managing passenger information, and other airline operations.
Telecommunication: Used for managing customer accounts, billing, and network information.

Before DBMS, organizations stored data in operating system files (file-processing systems).
File-processing systems have disadvantages like:
- Data Redundancy and Inconsistency: Information duplicated across files, potentially leading to inconsistencies.
- Difficulty in Accessing Data: Retrieving specific data from various files in different formats is difficult.
- Data Isolation: Data scattered across files makes it challenging to write new applications for data retrieval.
- Integrity Problems: Ensuring data consistency and meeting defined constraints can be difficult.
- Atomicity Problems: Failures during updates might leave the database in an inconsistent state.
- Concurrent Access Anomalies: Issues arise when multiple users access and modify data simultaneously.
- Security Problems: Controlling access to data and preventing unauthorized modifications is difficult.

DBMS provides users with an abstract view of data, hiding storage and maintenance details.
Data Abstraction is used to simplify user interactions with the system and address efficiency needs.
Physical Level: Describes how data is physically stored in the database, including low-level data structures.
Logical Level: Defines which data is stored and their relationships to each other, representing the overall structure of the database.
View Level: Presents subsets of the database for specific users, providing customized views of the data.
Instances and Schemas: A snapshot of the database at a particular moment is called an instance. The overall design of the database is called the schema.
Physical Data Independence: Application programs remain independent of the physical schema, allowing changes to the physical storage without needing changes to the application.