Object oriented database model
- 2. history The first of this model was the semantic data model (SDM) developed by M. Hammer and D. Mcleon and published in 1981 in their database description with SDM : A Semantic Database Model
- 3. Since SDM is an object- oriented data model (OODM). In turn the OODM becomes the basis for the object oriented database model with the manage of through an object oriented database management system (OODBMS)
- 5. In the object oriented data model the (OODM). Both data and their relationship are contained in a single structure known us an object.
- 6. An object includes information about relationship between the facts within the object, as well as information about its relationship with other objects.
- 7. It is said to be ‘’SEMANTIC DATA MODEL’’
- 8. The OO Data model components An object is the abstraction of the real- word entity. An object represents only one occurrence of entity.
- 9. Attributes describe the property of an object.
- 10. example PERSON NAME SOCIAL NUMBER DATE OF BIRTH
- 11. Objects that are similar in characteristics are grouped in class.
- 12. Class: is a collection of similar objects with shared structure ( attributes) and behavior (method) Method: represents areal word action such as finding a selected person’s name, changing person’s name or printing a persons address.
- 13. Classes are organized in class hierarchy. The class hierarchy resembles an up side down tree in which each class has only one parent.
- 14. PARENT PERSON COTUMER EMPLOYEE
- 15. Inheritance is the ability of an object within the class hierarchy to inherit the attributes and methods of the class above it.
- 17. Unified modeling language : describes a set of diagrams and symbols that can be used to graphically model a system.
- 18. UML class diagram: are used to represent data and their relationships within the larger UML object oriented system modeling language,
- 19. The object INVOICE representation of the INV__DATE invoice includes all INV__NUMBER INV__SHP__DATE related objects within INV__TOTAL the same box. The connectivity is (1 and COTUMER many)indicate the 1 relationship of the LINE related objects to the M invoice.