Object oriented database model

Object oriented database model

• 1.
  OBJECT-ORIENTED DATABASE MODEL
• 2.
  history The first ofthis 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
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   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)
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  OBJECT-ORIENTED DATABASE MODEL
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   In the object oriented data model the (OODM). Both data and their relationship are contained in a single structure known us an object.
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   An object includes information about relationship between the facts within the object, as well as information about its relationship with other objects.
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  It is saidto be ‘’SEMANTIC DATA MODEL’’
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  The OO Datamodel components  An object is the abstraction of the real- word entity. An object represents only one occurrence of entity.
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   Attributes describe the property of an object.
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  example PERSON NAME SOCIAL NUMBER DATE OF BIRTH
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   Objects that are similar in characteristics are grouped in class.
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   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.
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   Classes are organized in class hierarchy. The class hierarchy resembles an up side down tree in which each class has only one parent.
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  PARENT PERSON COTUMER EMPLOYEE
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   Inheritance is the ability of an object within the class hierarchy to inherit the attributes and methods of the class above it.
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   Unified modeling language : describes a set of diagrams and symbols that can be used to graphically model a system.
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   UML class diagram: are used to represent data and their relationships within the larger UML object oriented system modeling language,
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   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.