It is a system offering DBMS facilities in an object-oriented programming environment.
Data is stored as objects and can be interpreted only using the methods specified by its class.
For example, a relational query to know whether an employee named Pokemon is employed in the Detroit subsidiary of the Ford company is
SELECT EmplNo
FROM Company, Subsidiary, SubsEmpl, Employee
WHERE Company.Name = 'Ford'
AND Company.CompanyID = Subsidiary.CompanyID
AND Subsidiary.Location = 'Detroit'
AND Subsidiary.CompanyID = SubsEmpl.CompanyID
AND Subsidiary.NameSubs = SubsEmpl.NameSubs
AND SubsEmpl.Empl = Employee.EmplNo
AND Employee.Name = 'Pokemon';
This query could be stated in an object-oriented adaptation of SQL using path expressions:
select e
from e in Employee, c in Company, s in Subsidiary
where c.Name = 'Ford' and
s in c.Subsidiaries and
s.Office.Location = 'Detroit' and
e in s.Employees and
e.Name = 'Pokemon';