Levels of Abstraction:-

Physical level: Describes how a record (e.g., customer) is stored.

Logical level: describes data stored in database, and the relations 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