Database Management System Lecture 11: Inheritance and Entity-Relationship Model, Slides of Introduction to Database Management Systems

Download Database Management System Lecture 11: Inheritance and Entity-Relationship Model and more Slides Introduction to Database Management Systems in PDF only on Docsity! Database Management System Lecture - 11 Docsity.com Inheritance Gen/Spec relationship results inheritance between supertype and subtypes Subtypes inherit or get all the attributes of supertype Docsity.com Specifying Constraints Completeness constraint  Total specialization rule  Partial specialization Disjointness constraint  Disjoint rule  Overlap rule Docsity.com Completeness Example 1 Docsity.com Completeness Example 2 Docsity.com Subtype Discriminator To determine the subtype of a supertype instance Place an attribute in the supertype whose value determines the subtype type Docsity.com Disjoint Discriminator Docsity.com Overlap Discriminator Docsity.com Entity reflects entity type, entity instance and entity set Entity types are classified into weak and regular entity types Regular ETs can exist independently and weak ETs can’t Docsity.com Regular Entity Type Weak Entity Type NAME NAME Symbols Docsity.com Attribute represents a property or characteristic of an ET Attribute can be Simple Composite Multi-valued Derived Docsity.com Unary, Binary and Ternary Rships Docsity.com Relationships have cardinalities Cardinalities can be One to one One to many Many to one Many to many Docsity.com Minimum and maximum cardinalities are also specified in the E-R data model Different notations are used in E-R data model to represent cardinalities Docsity.com Docsity.com Prog_ID CGPA STUDENT Address Sem_joi nn Phone #StudID Fname Sname PROGRAM Descrip Max_Du ra Prog_ID COURSE CTitle Course_ id Prog_ID Crd_Ho u RESULT Semest er Prog_ID Stuid_id COURSES OFFERED CSeme s Course_ id Prog_ID Semest er Prog_ID Quiz EVALUATION Shift Assign Section #StudID Course_ Id Semest er Final Midterm Grade Attempt Docsity.com Database Management System Lecture - 11 Docsity.com