April 2003
Beginner to intermediate
380 pages
12h 25m
English
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Mapping Approaches
Several approaches can be used to establish a mapping between your persistent Java classes and a relational schema:
- Generate a relational schema from your persistent Java classes
If you are developing a new application in Java and you do not have an existing relational database schema, you can let the JDO implementation generate a relational schema from your object model. This approach is commonly called forward engineering the model. This approach yields a high level of development productivity because all of the schema design and mapping work is done automatically by the JDO implementation. The JDO specification does not require support for the automatic generation of a schema. Some implementations do not support this approach and require you to define the mapping to an existing schema. Many of the implementations that do support schema generation let you specify some metadata to help direct the algorithms generating the schema.
- Generate your persistent Java classes from a relational schema
In many cases, you may already be using a relational database schema and you would like to write a new application with an object view of the data. In this scenario, many implementations provide tools you can use that analyze your relational schema and generate a Java object model for you. This approach lets you develop an object-oriented Java application quickly. It is commonly called reverse-engineering the model.
- Define a mapping between Java classes and a relational schema ...
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