One disadvantage of OODBs is poor adoption among the community. If we turn to a relational database, which is fairly common, complex objects are more difficult to integrate into the table construct. The objects of the source code can simply be incorporated into the database. When working with object-oriented programming languages, like Java for example, an object database is advantageous. The choice of database type heavily depends on the individual application. If we retrieve our object via its unique ID, all of its related attributes and methods are directly available. At the same time, however, the object also has a connection to the class ‘Leisure activities’. The class ‘Bicycles’ is in turn a subcategory of ‘Vehicles’, which also contains ‘Cars’. Inside the same class, for example, we might also find a blue and a green bicycle. This object is then simultaneously part of the class ‘Bicycles’. It is red, you can ride it, it has a saddle, and so on. Assume we are saving the concrete object of a bicycle as an object-oriented unit with all of its properties and methods. In this way, objects can be easily retrieved again after they have been saved. To address the various objects, the corresponding database management system automatically assigns a one-off identification to each unit. Simple objects can be combined with complex objects. This breaks up the strict hierarchy and makes sure that the objects are interlinked. At the same time, objects in one class can also be connected with other classes.
Within such a construct, subclasses assume the properties of higher-level classes and expand on these with their own attributes.
This generates a hierarchy of classes and subclasses. Or, to put it more accurately: an object is a concrete unit in an abstract class. In turn, objects are brought together in classes. As in programming, each object has certain activities that it can carry out. This is where the databases’ proximity to object-oriented programming languages becomes clear. Alongside the attributes, methods are also stored in the objects. Instead of distributing everything across different tables, then, the data can be retrieved in one package. In this way, all of the information is directly available. In other words, a data set and all its attributes are combined with an object.
The object-oriented database model ties related packages together.
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