A Non-Relational Representation (Cont.)
Automobiles
It is composed of a drive and car body, with the drive consisting of an engine and gearing, and the engine being characterized by its horse-power and cubic capacity.
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OttoEngine: [
HP: Integer,
cc: Integer ]
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Automobile is-a Vehicle: [
Drive: VehicleDrive,
Carbody: String ]
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VehicleDrive: [
Engine: OttoEngine,
Gearing: String ]
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The Query Problem Solved
The query from the previous slide to know whether an employee named Pokemon is employed in the Detroit subsidiary of the Ford company is displayed again:
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';
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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';
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Doctor: “I’m sorry but you suffer from a terminal illness and have only ten to live.”
Patient: “What do you mean, ten? Ten what? Months? Weeks?!”
Doctor: “Nine.”
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