Database Systems Flashcards

Information, Data, and Databases

• Data: Raw facts and figures.
• Information: Processed data that is meaningful.
• Database: Organized collection of related data managed by a DBMS.
• Database Management System (DBMS): Software for creating and maintaining databases.
• Database System: DBMS software + data (+ applications).

Evolution of Database Systems

• Early DBMS (1960s): Based on file systems with limited capabilities.
• Hierarchical Data Model: Tree-based model (e.g., IBM's IMS).
• Network Data Model: Graph-based model, allowing multiple parent and child records.
• Relational Database Systems (1970s): Defined by Edgar Frank "Ted" Codd.
  • Based on relations.
  • SQL (developed by IBM in 1974) became the standard query language.
  • Oracle v.2 (1979): First commercial RDBMS using SQL.

Relational Database Example and SQL

• Example shows BOOK relation with attributes like Title, Author, Publisher, Year.
• SQL INSERT, DELETE, UPDATE, and SELECT examples are provided.

Trends in Database Systems

• Smaller systems: DBMS available for PCs and mobile devices.
• Bigger systems: Databases storing petabytes of data.

Information Integration

• Joining information from multiple related databases.
• Approaches:
  • Data warehouses: Central database with periodically copied and translated data.
  • Middleware (Mediator): Integrated model of data with translation between models.

DBMS Components

• Includes database users, database language (DDL, DML), and relational databases.

Database Users

• Database Administrators: Authorize access, coordinate, monitor use, manage resources.
• Database Designers: Define content, structure, constraints, and transactions.
• Database End Users: Use data for queries, reports, and updates.

DDL - Data Definition Language

• Used for defining data structure (schema).
• Commands: CREATE, ALTER, DROP.

DML - Data Manipulation Language

• Used for retrieving, inserting, deleting, and updating data.
• Subsystems:
  • Answering the query: Parsing, optimizing (query compiler), and executing (execution engine).
  • Transaction processing: Managing groups of database operations (transactions).

Trends of DB Design and DBMS

• Non-relational databases (NoSQL):
  • Examples: MongoDB, Redis.
• Multi-model databases:
  • Examples: Oracle Database, ArangoDB.