Hello,

I'm new learner on EJB and now I'm working on a project which need to
do SQL to EJB QL translation. I went through the specification 2.0 of
EJB QL released by Sun, I'm not quite understand the following words
regarding to the SELECT clause of EJB QL:

"In the case of a find method, the SELECT clause is restricted to
contain either a single range variable or a single value path
expression that evaluates to the abstract schema type of the entity
bean for which the finder method is defined.
Because finder method cannot return arbitrary types, the SELECT clause
of an EJB QL defined for a finder method must always correspond to the
abstract shcema type fo the entity bean for which the finder method is
defined.In contrast, the SELECT clause of a query defined for a select
method can return the abstract schema types of other entity beans or
the values of cmp-fields."

As my understanding, I think the SELECT clause of finder method can
only contain a single range variable instead of single value path
expresson, it should have only one format, which is "SELECT [DISTINCT]
OBJECT(identification_variable)".

For example: the query below is defined in OrderBean
findByProductType();
SELECT OBJECT(o) FROM Order o, IN(o.lineItems) l
WHERE l.product.product_type = 'schoolsupplies'

how it could be a single value path expression , I think this format
can only be used in Select method.

Another question is, EJB QL 2.0 does not support subquery and EXIST,
does this mean that a SQL query with subquery or EXIST clause can't be
translated to EJB QL?

I don't know if I'm correct or not. I'd appreciate if anybody can help
me with this.

Thanks!
Maggie