Hello Thambu,
Thanks for you reply. I was not attempting to create an entity bean for a non-updatable entity. What I was trying to do was 'Home business method' whose purpose in case of CMP, according to the Spec, is to make batch select operations possible and to return a sigle or collection of non-ejb type values(as opposed to findBy methods). Now it happens that the select operation that I am attempting requires GROUP BY and HAVING clause. TitleAuthor table is an updatable relationship table with two unidirectional One-Many relationships with tables Title and Author. To figure out titles with multiple authors, I need to execute the following query.
select t.title_id, t.title, t.price, t.pubdate, a.au_id,a.au_fname,a.au_lname, ta.royaltyper
from Title t, (
select ta.*
from TitleAuthor ta,
(
select ta.title_id
from TitleAuthor ta
group by ta.title_id
having count(ta.title_id) > 1
) tb
where ta.title_id = tb.title_id
) ta, Author a
where t.title_id = ta.title_id
and a.au_id = ta.au_id
order by t.title_id
There is no way I can do this query with EJB-QL.
However, in theory, I should not say that it is impossible to do this in CMP, but I would have to grab all the entities of TitleAuthor table and then perform the above logic programmatically in
Java. Which is practically inefficient and would be asinine of me to do so.
In such scenarios looks like BMP, or if allowed to use Entity beans at all, DAO/JDBC would more efficient.
Thanks
