1. Object-Oriented Databases
Chapter 11
Object-Oriented Databases
Database Systems: Design, Implementation, and Management, Fifth Edition, Rob and Coronel

2. In this chapter, you will learn:
What basic concepts govern OO systems
What effect OO concepts are likely to have on data modeling and design
How OO features are related to the more traditional relational and E-R models
What the basic features of an OO database management system (OODBMS) are
About the advantages and disadvantages of OODBMSs
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

3. Object Orientation Object Orientation OO Contribution areas
Set of design and development principles
Based on autonomous computer structures
known as objects
OO Contribution areas
Programming Languages
Graphical User Interfaces
Databases
Design
Operating Systems
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

4. Evolution of OO Concepts
Concepts stem from object-oriented programming languages (OOPLs)
Ada, ALGOL, LISP, SIMULA
OOPLs goals
Easy-to-use development environment
Powerful modeling tools for development
Decrease in development time
Make reusable code
OO Attributes
Data set not passive
Data and procedures bound together
Objects can act on self
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

5. OO Concepts: Objects Abstract representation of a real-world entity
Unique identity
Embedded properties
Ability to interact with other objects and self
OID
Unique to object
Not a primary key
Attributes
Called instance variables
Domain
Object state
Object values at any given time
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

6. OO Concepts: Objects (con’t.)
Methods
Code that performs operation on object’s data
Has name and body
Messages
Invokes method
Sent to object
Classes
Collection of similar objects
Shares attributes and structure
Protocol
Represents object’s public aspect
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

7. OO Concepts: Objects (con’t.)
Class hierarchy
Code that performs operation on object’s data
Has name and body
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

8. Object Characteristics
Figure 11.7
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

9. Class Hierarchy Superclass Subclass Class lattice Figure 11.8
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

10. Inheritance
Ability of object to inherit the data structure and behavior of classes above it
Single inheritance
Class has one immediate superclass
Figure 11.9
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

11. Inheritance (con’t.) Multiple
Class has more than one immediate superclass
Figure 11.10
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

12. Method Overriding Method redefined at subclass level Figure 11.12
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

13. Polymorphism
Allows different objects to respond to same message in different ways
Figure 11.13
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

14. Abstract Data Types (ADT)
Describes a set of similar objects
Differs from conventional data types
Operations are user-defined
Uses encapsulation
Definitions needed for creation
Name
Data representation
Abstract data type operations and constraints
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

15. Object Classification
Simple
Only single-valued attributes
No attributes refer to other object
Composite
At least one multivalued attribute
Compound
At least one attribute that references other object
Hybrid
Repeating group of attributes
At least one refers to other object
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

16. Characteristics of OODM
Supports complex objects
Must be extensible
Supports encapsulation
Exhibit inheritance
Supports object identity
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

17. OO vs. E-R Model Components
Table 11.3
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

18. Shared Representation for all Objects of the Class Person
Figure 11.14
Figure 11.15
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

19. Referential Sharing of Objects
Figure 11.19
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

20. Class-Subclass Relationship
Figure 11.21
Figure 11.20
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

21. Interobject Relationships
Attribute-Class Link
Object’s attribute references another object
Relationship Representation
Related classes enclosed in boxes
Double line on right side indicates mandatory
Connectivity indicated by labeling each box
1:M
M:N
M:N with an Intersection Class
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

22. 1:1 and 1:M Relationships Figure 11.24
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

23. Employee-Dependent Relationship
Figure 11.25
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

24. Representing the M:N Relationship
Figure 11.26
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

25. Representing the M:N Relationship with Associated Attributes
Figure 11.27
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

26. Representing the M:N Relationship with Intersection Class
Figure 11.28
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

27. Object Space Representation
Figure 11.29
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

28. Late and Early Binding Late binding Early binding
Data type of attribute not known until runtime
Allows different instances of same class to contain different data types for same attribute
Early binding
Allows database to check data type at compilation or definition time
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

29. OODM vs. E-R Data Models Object, Entity, and Tuple
OODM object has behavior, inheritance, and encapsulation
OO modeling more natural
Class, Entity Set, and Table
Class allows description of data and behavior
Class allows abstract data types
Encapsulation and Inheritance
Object inherits properties of superclasses
Encapsulation hides data representation and method
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

30. OODM vs. E-R Data Models (con’t.)
Object ID
Not supported in relational models
Relationships
OODM
Interclass references
Class hierarchy inheritance
Relational models
Value-based approach
Access
Relational models
SQL
OODM
Navigational
Set-oriented access
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

31. OODBMS
Database management system integrates benefits of typical database systems with OODM characteristics
Handles a mix of data types
Follows OO rules
Follows DBMS rules
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

32. OO and Database Design
Provides data identification and the procedures for data manipulation
Data and procedures self-contained entity
Iterative and incremental
DBA does more programming
Lack of standards
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

33. OODBMS Advantages More semantic information
Support for complex objects
Extensibility of data types
May improve performance with efficient caching
Versioning
Reusability
Inheritance speeds development and application
Potential to integrate DBMSs into single environment
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

34. OODBMS Disadvantages Strong opposition from the established RDBMSs
Lack of theoretical foundation
Throwback to old pointer systems
Lack of standard ad hoc query language
Lack of business data design and management tools
Steep learning curve
Low market presence
Lack of compatibility between different OODBMSs
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

35. OO Influences on Relational Model
Extensibility of new user-defined (abstract) data types
Complex objects
Inheritance
Procedure calls (rules or triggers)
System-generated identifiers (OID surrogates)
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel

36. The Next Generation of DBMS
Object-oriented database systems
Artificial intelligence systems
Expert systems
Distributed database
The Internet
Database Systems: Design, Implementation, & Management, 5th Edition, Rob & Coronel