3 - Extended Entity-Relationship(EER) Model (Lecture...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Extended Entity-Relationship(EER) Model (Lecture Session-3) Chapter 4 Monday, January 18, 2010 1 DLPD, BITS-Pilani. Prepared by Dr.R. Gururaj, Asst.Professor of CS
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Monday, January 18, 2010 DLPD, BITS-Pilani. Prepared by Dr.R. Gururaj, Asst.Professor of CS 2 Contents 1.What is EER 2.Subclass, Super class 3.Inheritance 4.Constraints 5.Notations
Background image of page 2
Why EER Some applications like –GIS, CAD/CAM, Telecommunication Have more complex requirements than normal database applications. To meet the requirements semantic data modeling concepts were incorporated into Conceptual data modeling such as ER modeling. The result is EER stands Extended ER modeling or Enhanced ER modeling The additional EER concepts are used to model applications more completely and more accurately. EER includes some object-oriented concepts, such as inheritance Monday, January 18, 2010 3 DLPD, BITS-Pilani. Prepared by Dr.R. Gururaj, Asst.Professor of CS
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Monday, January 18, 2010 DLPD, BITS-Pilani. Prepared by Dr.R. Gururaj, Asst.Professor of CS 4 Additional concepts: subclasses/super classes specialization/generalization attribute and relationship inheritance These are fundamental to conceptual modeling.
Background image of page 4
Monday, January 18, 2010 DLPD, BITS-Pilani. Prepared by Dr.R. Gururaj, Asst.Professor of CS 5 Subclass of an Entity type An entity type may have additional meaningful subgroupings of its entities Example: EMPLOYEE may be further grouped into: SECRETARY, ENGINEER, TECHNICIAN, … Based on the EMPLOYEE’s Job MANAGER EMPLOYEEs who are managers SALARIED_EMPLOYEE, HOURLY_EMPLOYEE Based on the EMPLOYEE’s method of pay EER diagrams extend ER diagrams to represent these additional subgroupings, called subclasses or subtypes
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Monday, January 18, 2010 DLPD, BITS-Pilani. Prepared by Dr.R. Gururaj, Asst.Professor of CS 6
Background image of page 6
Monday, January 18, 2010 DLPD, BITS-Pilani. Prepared by Dr.R. Gururaj, Asst.Professor of CS 7 Each of these subgroupings is a subset of EMPLOYEE entities Each is called a subclass of EMPLOYEE EMPLOYEE is the superclass for each of these subclasses These are called superclass/subclass relationships: EMPLOYEE/SECRETARY EMPLOYEE/TECHNICIAN EMPLOYEE/MANAGER
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/14/2010 for the course CSE IS ZC332 taught by Professor Shailendrasshekhawat during the Summer '10 term at Birla Institute of Technology & Science.

Page1 / 25

3 - Extended Entity-Relationship(EER) Model (Lecture...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online