Basic Concepts Entity Sets a database can be modeled as a collection of entities relationship among entities An entity is an object that exists and is distinguishable from other objects Example: specific person, company, event, plant Entities have attributes Example: people have names and addresses An entity set is a set of entities of the same type that share the same properties Example: set of all persons, companies, trees holidays Database System Concepts 2.2 OSilberschatz. Korth and SudarshanDatabase System Concepts 2.2 ©Silberschatz, Korth and Sudarshan Basic Concepts Entity Sets A database can be modeled as: a collection of entities, relationship among entities. An entity is an object that exists and is distinguishable from other objects. Example: specific person, company, event, plant Entities have attributes Example: people have names and addresses An entity set is a set of entities of the same type that share the same properties. Example: set of all persons, companies, trees, holidays