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.
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.
15. Inheritance is the ability of an object
within the class hierarchy to inherit the
attributes and methods of the class
above it.
16.
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.
