- on is more SQL thus less intrusive
- instanceof is cool, but casting is more useful
where ( p instanceof Cheque and ((Cheque) p).paperType = :paperType) or (p instanceof CreditCard and ((CreditCard) p).pinCode)
Gavin King wrote:
One of the main reasons we migrated to the new query parser was to allow for easier extension of HQL. We didn't actually make much in the way of HQL extensions in 3.0 (except for UPDATE/DELETE, CASE and EJB-QL functions). I've been wondering what new cool stuff we could consider for 3.1.
First, we need to add a way to add extra conditions to outer joins. Eg:
from Order ord left join ord.lines line on line.deleted is false where ...
But perhaps "on" is the wrong keyword, since it is an "extra" join condition. Perhaps "filter by"?
from Order ord left join ord.lines line filter by line.deleted is false where ...
I'm not sure.
Next, it's about time we had a reliable instanceof operator:
from Payment p where p instanceof Cheque or ....
Next, I'm considering adding more query-level control over fetching strategies
from Order ord subselect fetch ord.lines
from Order ord select fetch ord.lines
from Order ord batch fetch ord.lines
from Order ord batch size 10 fetch ord.lines
Finally, we need to grapple with the problem of supporting expressions in the select clause.
Do you think we could and should support the ANSI SQL style periods and temporal operators (overlaps, during, before, after, etc.) in a portable way?
from Contract c where [c.effectiveStartDate, c.effectiveEndDate] overlaps (:start, :end]
(Unfortunately, Java has no Period or Interval class that we could create a standard Hibernate Type for.)
Any other ideas?
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