PPT Slide
The Relational DBMS Revolution
- The pre-relational era (1970's)
- Graph-based data models
- Hierarchical model (e.g., IMS)
- Network model (e.g., Codasyl)
- Low-level, navigational interfaces
- Labor-intensive and error-prone
- The relational era (1980's)
- Simple, abstract data model
- Database = set of relations ("tables")
- 3 schema levels: views, base tables, physical schema
- Algebra of set-oriented operations
- High-level, declarative interfaces
- SQL, Quel, QBE
- Embedded languages, 4GLs