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Slide 16.13: Generating and modifying objects Slide 16.15: Generating new classes, instances, and operations Home         Print version

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Desired Properties (Cont.)

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Generating and Modifying Objects (Cont.)

• Insert a new vehicle for which an object manufacturer already exists.
  
  
  2. Insert a new vehicle made by that manufacturer.
     
     

     view source print? 1 INSERT NEW( model, manufacturer, color ) 2   VALUES( 'Mondeo', m, 'red' ) INTO vehicle;

     
     

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     view source print? 1 INSERT NEW( model, manufacturer, color ) 2   VALUES( 'Mondeo', 3     SELECT f FROM f IN company WHERE name = 'Ford', 'red' ) 4   INTO vehicle;

  
  An appropriate flatten-operator should be available because the query defines a set and the manufacturer of a vehicle is not set-values.
  
  
• Modification operations may also have an effect on existing collections. For example, John Smith is to be employed in Ford‘.s subsidiary in Chicago. The following procedure is required:
  
  
  1. Insert John Smith into the class employee.
  
  
  2. Select the object from the class subsidiary of the company with the name Ford and the location “Chicago” in its address.
  
  
  3. Insert the object employee with name John Smith into the set employees of this subsidiary.

Generating New Classes, Instances, and Operations
A data manipulation language of an OODBS must allow views to be defined on a given database state. In RDBMS, the VIEW command creates a logical (virtual) table. This logical table exists only in memory, and yet it may be treated as though it were a real table.

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Slide 16.13: Generating and modifying objects Slide 16.15: Generating new classes, instances, and operations Home         Print version

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I went to the doctors earlier today with hearing problems.           He said “Can u describe the symptoms?”           I said “Homers a fat guy and Marge has blue hair.”