Hi,
kishore talagadadeevi wrote:
Hi,
I would like to know whether any known issues with ODMG api in handling multiple tables by mapping to a single class.
Mapping a single class to multiple tables was currently not supported (insert does not work, reading should work but I never test this) by ODMG (PB-api support this feature).
I need to just retrieve the data only .
as said above, this could be work with odmg.
I have seen some documentation
explaining a mapping of a class to multile tables. But I want to know whether it is going to
work for my scenario or not before starting my coding ....
Requirement: -----------------
I have three independent tables .
All three tables have part_num and part_serial as part of composite primary key in addition to other columns.
Question: How do I retrieve qty,cost and size by joining all three tables on part_num and
part_serial columns using OJB ???
How do I define this scenario as a class descriptor in repository.xml file ???
Don't know if I understand your question, but nevertheless I will try answer something ;-)
You can use 'Extents' with a base interface. http://db.apache.org/ojb/docu/guides/advanced-technique.html#Extents
interface Part
{
get/setNum
get/setSerial
{PartA,...C implement interface Part
In repository file declare class-descriptor for PartA,...C (with PK attribute for num + serial) and
define these classes as extents of Part
<class-descriptor class="Part"> <extent-class class-ref="PartA" /> <extent-class class-ref="PartB" /> <extent-class class-ref="PartC" /> </class-descriptor>
Criteria crit = new Criteria();
[crit.addEqualTo("fieldName", value);]
crit.addEqualTo("partNum", 12);
crit.addEqualTo("serial", 123);
Query q = QueryFactory.newQuery(Part.class, crit);
Collection result = broker.getCollectionByQuery(q);Will return all Part classes (PartA, ...C) with part_num 12 and part_serial 123
regards, Armin
TABLE_PARTA: -------------------------
part_num(pk) part_serial(pk) system(pk) qty
TABLE_PARTB ---------------------
part_num(pk) part_serial(pk) type(pk) cost
TABLE_PARTC : ----------------------- part_num(pk) part_serial(pk) dimension(pk) size
Please throw some light on the above mentioned issue ...
Thanks in advance ...
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