Download presentation

Presentation is loading. Please wait.

Published byMariano Brewton Modified over 2 years ago

1
Complex entities and relationships Case examples are from the book: Lars Fank Databaser Teori og Praksis ISBN

2
Short repetition: Many-to-many, One-to-many, trees, and network relationships:

3
Repetition: One-to-many relationships

4
Repetition: Many-to-many relations.

5
Different illustrations of tree structure relationships:

6
Different illustrations of network structure relationships:

7
Relationship degree Type of relationshipRelationship degree One-to-many relationshipBinary Many-to-many relationshipBinary One-to-one relationshipBinary Tree structure relationshipUnary Network relationshipUnary Order relationshipUnary Relationship of degree NN-ary

8
Different illustrations of simple relationships of order 3.

9
Different illustrations of simple relationships of degree 3.

10
ER and Bachman illustrations of the relationship of order three.

11
An ER relationship need not be implemented as a table or a forign key How would you convert the Bachman diagram to an ER-diagram with normalized tables?

12
Entities and relationships must not be connected directly in ER-diagrams. Therefore, ER-diagrams need a pseudoentity if two relationships need to be connected

13
ER relationships may be viewed as Bachman entities depending on the application area.

14
ER versus Bachman diagrams: In this course you should not use ER-diagrans because they are ambiguous

15
End of session Thank you !!!

Similar presentations

© 2016 SlidePlayer.com Inc.

All rights reserved.

Ads by Google