Eer model and relationship to the oo ppt

Object-Oriented Data Modeling - ppt video online download

eer model and relationship to the oo ppt

Outline EER Model Concepts Includes all modeling concepts of basic ER and more accurately EER includes some object-oriented concepts, such as. Basic concepts of OO and OR models; Extensions at conceptual modeling; Mapping . Enhance Entity Relationship (EER – Chap 4, Elmasri/Navathe); Pictogram Enhanced . az-links.info~vatsavai/az-links.info; Main – Database. Database design process; Entity/Relationship Model. Entity sets In OO terminology, an entity set is similar to a class, and an entity similar to an instance.

A binary association is bidirectional. The name of an association establishes only one direction.

Chapter Object-Oriented Data Modeling - ppt video online download

Overlapping Complete total specialization vs. Defines the form or protocol of the operation, but not its implementation.

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The implementation of an operation. The same operation may apply to two or more classes in different ways 30 Figure — Polymorphism, abstract operation, class-scope attribute, and ordering This operation is abstract…it has no method at Student level Class-scope attributes — only one value common to all instances of these clases Methods are defined at subclass level 31 Overriding Inheritance Overriding: The process of replacing a method inherited from a superclass by a more specific implementation of that method in a subclass.

An object is an instance of more than one class.

Extended ER Features, Generalization, Specialization, Aggregation in DBMS with Example

A class inherits features from more than one superclass. A part-of relationship between a component object and an aggregate object. A stronger form of aggregation in which a part object belongs to only one whole object and exists only as part of the whole object.

eer model and relationship to the oo ppt

ER model and relational model use value-based identification Explicit identification OO model uses existence-based identification Implicit identification In OO model, the identifiers that we should create are the identifier attributes that are meaningful in the application. In a conceptual object-oriented model, an attribute should be single-valued.

Enhanced Entity-Relationship (EER) Model - ppt download

Therefore, a multivalued attribute should be transformed into a separate class and an 1: N association between the class and the new class. Transform a class in class diagram to a table 2.

eer model and relationship to the oo ppt

Transform an attribute of a class to a table column. In case a class does not have any explicit identifier, create a primary key usually of integer type for the table corresponding to that class.

Object-Oriented Data Modeling

For a table corresponding to a subclass, use the primary key of its superclass as its primary key. Specialized attributes and operations 23 b Abstract Patient class with two concrete subclasses Figure Examples of generalization, inheritance, and constraints cont. Defines the form or protocol of the operation, but not its implementation Method: The implementation of an operation Polymorphism: The same operation may apply to two or more different classes in different ways 26 Figure Polymorphism, abstract operation, class-scope attribute, and ordering This operation is abstract…it has no method at Student level Class-scope attributes—only one value common to all instances of these classes includes default values Methods are defined at subclass level 27 Overriding Inheritance Overriding: The process of replacing a method inherited from a superclass by a more specific implementation of that method in a subclass For Extension: An object is an instance of more than one class Multiple Inheritance: A class inherits features from more than one superclass 30 Figure Multiple inheritance 31 Aggregation Aggregation: A part-of relationship between a component object and an aggregate object Composition: A stronger form of aggregation in which a part object belongs to only one whole object and exists only as part of the whole object Recursive Aggregation: But, these parts can exist without being installed into a computer.