gangster has jobs 

gangsterId

gangster

job has gangsters 

name

job

Listing 9 11, The jbosscmp jdbc.xml Relation table Mapping 

The relation table mapping element contains a subset of the options available in the entity 

element, and these elements are discussed in Chapter 4 of the JBossCMP Documentation. 

Queries 

Another powerful new feature of CMP 2.0 is the introduction of the EJB Query Language 

(EJB QL) and ejbSelect methods. In CMP 1.1, every EJB container had a different way to 

specify finders, and this was a serious threat to J2EE portability. In CMP 2.0, EJB QL was 

created to specify finders and ejbSelect methods in a platform independent way. The 

ejbSelect method is designed to provide private query statements to an entity 

implementation. Unlike finders, which are restricted to only return entities of the same type 

as the home interface on which they are defined, ejbSelect methods can return any entity 

type or just one field of the entity. 

EJB QL is beyond the scope of this guide, so only the basic method coding and query 

declaration will be covered here. For more information, see Chapter 11 of the 

Enterprise 

JavaBeans Specification Version 2.0 Final Release

 or one of the many excellent articles 

written on CMP 2.0. 

94