Basic Concepts(Cont) Relationship sets A relationship is an association among several entities Example: Hayes depositor A-102 customer entity relationship set account entity A relationship set is a mathematical relation among n2 2 entities, each taken from entity sets {(e1e2,……en)le1∈E n Eny where (e1, e2, ., en)is a relationship Example: (Hayes, A-102)E depositor 标 Database System Concepts 2.6 @Silberschatz, Korth and SudarshanDatabase System Concepts 2.6 ©Silberschatz, Korth and Sudarshan Basic Concepts (Cont.) Relationship Sets A relationship is an association among several entities Example: Hayes depositor A-102 customer entity relationship set account entity A relationship set is a mathematical relation among n  2 entities, each taken from entity sets {(e1 , e2 , … en ) | e1  E1 , e2  E2 , …, en  En } where (e1 , e2 , …, en ) is a relationship Example: (Hayes, A-102)  depositor