Populate list by executing query with where clause

Question

Hi,
I m populating my list from database table using following command.
EntityManagerFactory emf = Persistence.createEntityManagerFactory("learning", new HashMap());
EntityManager em = emf.createEntityManager();
String query = "select d from Dept d";
List list = em.createQuery(query).getResultList();
My list is getting populated with all of rows in my database table(dept). The problem is, I cant use where clause in my query string.
String query = "select d from Dept d where d.dept_name='ANYNAME'";
Moreover I cant select even indivisual columns by using following line
String query = "select d.dept_code,d.dept_name from Dept d";
It looks like that my query is getting all rows from table as Object.
What to do to
1. put some where clause
2. get some particular colums instead of all columns
3. apply some table joins in query
plz help.

Answer 1

Hi Alex,
I misunderstood your question. You had mentioned "My list is getting populated with all of rows in my database table(dept). The problem is, I cant use where clause in my query string. "
I thought you might not have permissions to modify the code in the class, and that's why I suggested that you could write new classes.
1) write new classes,? means if I need just two columns from a table >(instead of all columns), do I need to write new class with just two >columns (getters and setters)?You can write a SQL statement anyway you want , there are no restrictions in JDBC , so if you need just 2 columns you can write a custom query for that.
"select column1 as a, column2 as be from table_name where column3 = xyz" etc.
2) Is not anyway to write SQL statement like
select dept_code,dept_name from dept where dept_name='anything'The above SQL is correct, it should work.
3) Stored procedures? can I get some example(code) to get an idea >how to implement complex queries with where clause and joinings >using stored procedures?Stored procedures are specific to the database you are using, Oracle has a particular syntax for store procdures.
You can call stored procedures from JDBC also, search on Google for
"Calling stored procedures from JDBC"
4) I m using hibernate. can I get any example of using hibernate own >query?Tutorial on Hibernate Query Language:
http://www.hibernate.org/hib_docs/v3/reference/en/html/queryhql.html