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Joins in Hibernate

Ritesh Singal
Greenhorn

Joined: Mar 31, 2006
Posts: 2
Hi!!!

There's problem in Hibernate.

I have three tables as :

Department(Dno,Dname)
Employee(Eno,Dno,Salary)
Project(Pno,Dno) i.e Here Dno represents The Department that controls that project.

Now I Want Output as :
Dname,sum(Salary),count(Project)

i.e. Total Salary paid to each Department and total number of projects controlled by each department.

i.e. Group by dno in Employee for Sum(Salary) and Group by dno in Project for count(*)
Then Join both results with Department to get desired results.


In Sql we write the Query as :

SELECT d.dname, a.s, b.c
FROM Department d,
(SELECT dno, sum(salary) s FROM Employee GROUP BY dno) a,
(SELECT dno, count(*) c FROM Project GROUP BY dno) b
WHERE d.dno=a.dno and a.dno=b.dno


I get the correct result from the above query.

Now Problem is how to write the same query in Hibernate.

DOES HIBERNATE SUPPORTS SUBQUERY IN FROM CLAUSE AS USED IN ABOVE SQL.


In java we have three classes as :

Department(dno,dname)
Employee(eno,salary and Object of Department dept)
Project(pno and Object of Department dept)


In hibernate I have write a query as :

SELECT d.dname,a.s,b.c
FROM Department d, (SELECT e.dept.dname dn,sum(salary) s FROM Employee e group by dn) a,
(SELECT p.dept.dname dnm, count(*) s FROM Project p group by dnm) b
Where d.dname = a.dn and a.dn = b.dnm

But Hibernate gives error in From clause where "(" starts.
I think Hibernate does not support Subquery in From clause.

Individually Employee group by and Project group by is alright in Hibernate.

Help me to Solve above Problem

Bye!!!
Paul Sturrock
Bartender

Joined: Apr 14, 2004
Posts: 10336

This is the same as your other post.


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subject: Joins in Hibernate