Question

I am using ireport-4.5.0,spring3.0.5RELEASE,jpa2. I have an entity class named as User and having the attributes as follow
userId,
userName,
password.I

Designed the jrxml by giving the fields as these three attributes names.If i give the jpa Query as From USer then it is working fine and giving the result. But i want the distinct values of userName(userName column allows duplicate values also)so i have given the jpaQuery as

SELECT userId,DISTINCT(userName),password FROM User 

Then i am not getting the result.What is the problem with the query.

Hi here i am giving the code i am using

public User getUsers() throws Exception{
 Query uQuery = entityManager.createQuery("SELECT u.userId,u.userName,u.password FROM User u GROUP BY u.userId,u.userName,u.password");
       List <User>listOfUsers = uQuery.getResultList();
       if (listOfUsers == null) {
           throw new ResourceNotFound();
        }
       for (Iterator iterator = listOfUsers.iterator(); iterator.hasNext();) {
            User userList = (User)iterator.next();

        }

       return userList;

Here i am getting the ClassCastException:java.lang.String cannot be cast to User.It is showing this exception in the for loop statement.I am new to JPA.Can you please explain how to iterate that list of objects.

Answer 1

You cannot put DISTINCT on a single column in JPQL or SQL.

You most likely need to use a group by,

SELECT u.userId,u.userName,u.password FROM User u group by u.userId, u.userName, u.password