Levels of Abstraction Physical level:describes how a record(e.g.,customer)is stored. Logical level:describes data stored in database,and the relationships among the data. type customer record customer id:string; customer_name string; customer_street:string; customer_city:integer; end; View level:application programs hide details of data types.Views can also hide information(such as an employee's salary)for security purposes. Database System Concepts-5th Edition,May 23,2005 1.6 ©Silberschat乜，Korth and SudarshanDatabase System Concepts - 5 1.6 ©Silberschatz, Korth and Sudarshan th Edition, May 23, 2005 Levels of Abstraction Physical level: describes how a record (e.g., customer) is stored. Logical level: describes data stored in database, and the relationships among the data. type customer = record customer_id : string; customer_name : string; customer_street : string; customer_city : integer; end; View level: application programs hide details of data types. Views can also hide information (such as an employee’s salary) for security purposes