Sorry, it was late when I made the last post. I was thinking about the Fetch Joins.
anonymous wrote : 4.4.5.3 Fetch Joins | An important use case for LEFT JOIN is in enabling the prefetching of related data items as a side effect | of a query. This is accomplished by specifying the LEFT JOIN as a FETCH JOIN. | A FETCH JOIN enables the fetching of an association as a side effect of the execution of a query. A | FETCH JOIN is specified over an entity and its related entities. | The syntax for a fetch join is | fetch_join ::= [ LEFT [OUTER] | INNER ] JOIN FETCH join_association_path_expression | The association referenced by the right side of the FETCH JOIN clause must be an association that | belongs to an entity that is returned as a result of the query. It is not permitted to specify an identification | variable for the entities referenced by the right side of the FETCH JOIN clause, and hence references | to the implicitly fetched entities cannot appear elsewhere in the query. | The following query returns a set of departments. As a side effect, the associated employees for those | departments are also retrieved, even though they are not part of the explicit query result. The persistent | fields or properties of the employees that are eagerly fetched are fully initialized. The initialization of | the relationship properties of the employees that are retrieved is determined by the metadata for the | Employee entity class. | SELECT d | FROM Department d LEFT JOIN FETCH d.employees | WHERE d.deptno = 1 anonymous wrote : | A fetch join has the same join semantics as a left outer join, except that the related objects specified on | the right-hand side of the join operation are not returned in the query result or otherwise referenced in | the query. Hence, for example, if department 1 has five employees, the above query returns five references | to the department 1 entity. | Extract from ejb-3_0-pfd-spec-persistence.pdf View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3923603#3923603 Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=3923603 ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=103432&bid=230486&dat=121642 _______________________________________________ JBoss-user mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/jboss-user
