tailieunhanh - Lecture Database system concepts (6/e): Chapter 22 - Silberschatz, Korth, Sudarshan

Chapter 22 - Object-based databases. This chapter covers objectbased databases. The chapter describes the object-relational data model, which extends the relational data model to support complex data types, type inheritance, and object identity. The chapter also describes database access from object-oriented programming languages. | Chapter 22: Object-Based Databases Database System Concepts, 6th Ed. ©Silberschatz, Korth and Sudarshan See for conditions on re-use Chapter 22: Object-Based Databases Complex Data Types and Object Orientation Structured Data Types and Inheritance in SQL Table Inheritance Array and Multiset Types in SQL Object Identity and Reference Types in SQL Implementing O-R Features Persistent Programming Languages Comparison of Object-Oriented and Object-Relational Databases Database System Concepts - 6th Edition ©Silberschatz, Korth and Sudarshan Object-Relational Data Models Extend the relational data model by including object orientation and constructs to deal with added data types. Allow attributes of tuples to have complex types, including non-atomic values such as nested relations. Preserve relational foundations, in particular the declarative access to data, while extending modeling power. Upward compatibility with existing relational languages. Database System Concepts - 6th Edition ©Silberschatz, Korth and Sudarshan Complex Data Types Motivation: Permit non-atomic domains (atomic ≡ indivisible) Example of non-atomic domain: set of integers,or set of tuples Allows more intuitive modeling for applications with complex data Intuitive definition: allow relations whenever we allow atomic (scalar) values — relations within relations Retains mathematical foundation of relational model Violates first normal form. Database System Concepts - 6th Edition ©Silberschatz, Korth and Sudarshan Example of a Nested Relation Example: library information system Each book has title, a list (array) of authors, Publisher, with subfields name and branch, and a set of keywords Non-1NF relation books Database System Concepts - 6th Edition ©Silberschatz, Korth and .