I'm trying to write an HQL query to select objects which contain an object in a child collection.
Example:
Contest Object
ContestID
ContestName
RequiredCountries -> one to many collection of Country objects
Country Object
CountryCode
CountryName
The sql equivalent of what i want:
SELECT * FROM CONTEST C
WHERE C.CONTESTID IN(SELECT CONTESTID FROM CONTEST_COUNTRY CC INNER JOIN COUNTRY CTRY ON
CC.COUNTRYCODE = CTRY.COUNTRYCODE WHERE COUNTRYCODE='USA')
OR
SELECT * FROM CONTEST C
WHERE EXISTS(SELECT CONTESTID FROM CONTEST_COUNTRY CC INNER JOIN COUNTRY CTRY ON
CC.COUNTRYCODE = CTRY.COUNTRYCODE WHERE COUNTRYCODE='USA' AND CC.CONTESTID=C.CONTESTID)
I have this hql, which works, but seems like not a good solution-
from Contest C
where (from Country where CountryCode = :CountryCode) = some elements(C.RequiredCountries)
I also consider joining with Country, but since I don't have an object class to represent the relationship, I wasn't sure how to join in HQL.
Anyone have any ideas or suggestions? This should be easy.
Answer
try this:
from Contest Ct, Country Cr
where Cr.CountryCode = :CountryCode
and Cr.Country in elements(Ct.RequiredCountries)