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From "Vadim Gritsenko (JIRA)" <j...@apache.org>
Subject [jira] Commented: (OJB-16) Support stored procedures in select by pk statement
Date Wed, 13 Apr 2005 16:07:18 GMT
     [ http://issues.apache.org/jira/browse/OJB-16?page=comments#action_62746 ]
     
Vadim Gritsenko commented on OJB-16:
------------------------------------

Ok, that one is easy.

> Ok, but how do the procedures get chosen?

As you can see, for retrieving objects by their identity always select-by-pk procedure is
used. Collections are always retrieved using select-by-fk procedure. References are converted
in the ObjectReferenceBroker into the Identity queries, so again, select-by-pk is used.

select-by-pk is implemented in SqlGeneratorDefaultImpl.getPreparedSelectByPkStatement - that's
where query by identity ends up.

select-by-fk is implemented using new Query class, constructed in QueryReferenceBroker.getFKQuery1toN
and converted to procedure call in the SqlGeneratorDefaultImpl.getPreparedSelectStatement.


> IMO it is unclear which one is used when I retrieve objects by a
> simple query,

What is a simple query? If it's query by identity, then select-by-pk is used. If it's query
by example, select-by-fk is used. If it's query by SQL, then it depends on your SQL (I use
stored procedures). If neither of those (like query by criteria), then behaviour as it is
now (select statement).


> or which one is used for retrieving the collection
> of B's within A.

select-by-fk is always used in this case, as you need to select instances of B using its foreign
key field aId.


> And if the by-fk procedure is used for the
> collection, where do the values come from ?

If you mean where B.aId is coming from: that what QueryReferenceBroker.getFKQuery1toN is for,
and it is invoked from getFKQuery, it creates query using passed to it A object instance.

Regards,
Vadim


> Support stored procedures in select by pk statement
> ---------------------------------------------------
>
>          Key: OJB-16
>          URL: http://issues.apache.org/jira/browse/OJB-16
>      Project: OJB
>         Type: New Feature
>   Components: PB-API
>     Versions: 1.0.x CVS
>     Reporter: Vadim Gritsenko
>     Assignee: Thomas Dudziak
>  Attachments: QueryByCriteriaBase.java, QueryByFKCriteria.java, SelectByFKProcedureDescriptor.java,
SelectByPKProcedureDescriptor.java, SqlProcedureFKStatement.java, db-ojb-patch.diff, db-ojb-selectbypk.diff,
xdoclet.diff
>
> This patch adds support for retrieving objects by primary keys through call to stored
procedure instead of using select statement.
> To activate the feature, add xdoclet tag to the class:
> /**
>  * @ojb.class table="MYBEAN"
>  * @ojb.selectbypk-procedure name="FIND_MYBEAN_BYID"
>  */
> public class MyBean {
>     /**
>      * @ojb.field primarykey="true"
>      */
>     Integer id;
> }
> And then, create stored procedure:
> CREATE OR REPLACE PACKAGE TYPES AS
>   TYPE CURSORTYPE IS REF CURSOR;
> END TYPES;
> /
> CREATE OR REPLACE FUNCTION FIND_MYBEAN_BYID (ANID IN MYBEAN.ID%TYPE)
> RETURN TYPES.CURSORTYPE AS
> RESULT TYPES.CURSORTYPE;
> BEGIN
>   OPEN RESULT FOR SELECT * FROM MYBEAN WHERE ID = ANID;
>   RETURN RESULT;
> END;
> /
> Patch is made against OJB_1_0_RELEASE branch.

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