1 Entity-Relationship Modeling

2 ER Graphical modeling technique Informal, understandable for laymen Coarse technique to design tables Provides rules of thumb for mapping to table structures

3 Entities and attributes

4 Relations (associations)

5 Recursive relations With roles

6 Weak entities

ISA-hierarchy

8 Cardinality & optionality ( 0,n) (1,1) optional mandatory

ERD -> relational schema

Solution 1 E1 (K1, A1, …, Am, K2) E2 (K2, B1, …, Bn) Solution 2 E1 (K1, A1, …, Am) E2 (K2, B1, …, Bn, K1)

ERD -> relational schema Solution 3 E1 (K1, A1, …, Am, K2) E2 (K2, B1, …, Bn, K1)

ERD -> relational schema Solution 4 E1 (K1, A1, …, Am) E2 (K2, B1, …, Bn) R (K1, K2)