1. Lab 3 Alternative ER Modelling Pearson Education © 2009

2. 2 ER Modeling u We learned how to create an ER model using an increasingly popular notation called Unified Modeling Language (UML). u There are tow additional notation that are often used to create ER models as following : –Chen Notation. –Crow’s Feet Notation. –( self learning ) Pearson Education © 2009

3. 3 The Chen notation for ER modeling Pearson Education © 2009 NotationMeaning Strong entity Weak entity Relationship Relationship associated with a weak entity Entity name Relationship name Relationship name

4. 4 The Chen notation for ER modeling Pearson Education © 2009 NotationMeaning Role name Recursive relationship with role names Attribute Entity name PK Simple name Multi valued Derived Attribute Relationship name Composite attribute Attribute

5. 5 The Chen notation for ER modeling Pearson Education © 2009 NotationMeaning One to one (1:1) relationship One to many (1:M) relationship many to many (M:N) relationship Relationship name 11 Relationship name 1M Relationship name MN

6. 6 The Chen notation for ER modeling Pearson Education © 2009 NotationMeaning Generalization/ specialization d: relationship is disjoint o: relationship is nondisjoint Double line : mandatory participation Single line : optional participation Super class Subclass d