ER models

1. Enhanced ER-diagram Prof. Sin-Min Lee Department of Computer Science CS157A Lecture 5

2. Database Modeling and Implementation Process Ideas ER Design Relational Schema Relational DBMS Implementation

7. RELATIONSHIPS (Cont…) carry books index wrote subject authors SS# name title libraries address isbn Subject matter

8. RELATIONSHIPS (Cont…) carry books index wrote subject authors SS# name title libraries quantity address isbn Subject matter

13. Works for Emp SS# name address Works for Emp SS# name address Primary keys: Emp: SS# Works-for: (empSS#, mgrSS#) Primary keys: Emp: SS# Works-for: (empSS#)

22. E-R Diagram With Aggregation

44. Example of a Specialization

51. Example of disjoint partial Specialization

54. Specialization / Generalization Lattice Example (UNIVERSITY)

57. Example of categories (UNION TYPES)

60. GENERALIZATION AND SPECIALIZATION sid student name is A graduate Undergrad Specialization Generalization

62. GENERALIZATION AND SPECIALIZATION sid student name graduate Undergrad Specialization Generalization d U U

64. GENERALIZATION AND SPECIALIZATION sid Emp name Part-time Salaried Specialization Generalization d U U

67. UML Example for Displaying Specialization / Generalization

68. Alternative Diagrammatic Notations Symbols for entity type / class, attribute and relationship

69. Notations for displaying specialization / generalization

70. Displaying attributes

71. Various (min, max) notations Displaying cardinality ratios