Relation Instance The current values(relation instance)of a relation are specified by a table An element t of r is a tuple, represented by a row in a table Attributes or columns customer-name customer-street customer-city Jones Main Harrison smith North Rve tupl Curr North Rve (or rows) Lindsay Park Pittsfield customer 标 Database System Concepts 3.6 OSilberschatz, Korth and SudarshanDatabase System Concepts 3.6 ©Silberschatz, Korth and Sudarshan Relation Instance The current values (relation instance) of a relation are specified by a table An element t of r is a tuple, represented by a row in a table Jones Smith Curry Lindsay customer-name Main North North Park customer-street Harrison Rye Rye Pittsfield customer-city customer attributes (or columns) tuples (or rows)