An Example for Hibernate Named Query with Aggregate Function

1. Does entity fit here?

I don't think so, we'd better have a VO or DTO to represent.

2. hbm.xml

<sql-query name="getCustomerInfo">
SELECT baseT.customer_id AS customerId,
phone,
currency,
account_type AS accountType,
active,
customer_type AS customerType,
follow_percentages AS followBetPercentages,
( Sum(IF(cust_trans_id IS NULL, 0, IF(accnt_trans_type = 'Credit', 0 - Round(amount, 2),
IF(accnt_trans_type = 'Debit', Round(amount, 2), 0)))) ) AS balance
FROM   (SELECT customerT.customer_id,
customerT.phone,
customerT.credit_limit,
customerT.currency,
customerT.account_type,
customerT.active,
customerT.customer_type,
CONVERT(Ifnull(customerT.follow_percentages, '') USING utf8) AS
follow_percentages
FROM   (SELECT customer.customer_id,
phone,
credit_limit,
currency,
customer.active,
customer_type,
account_type,
Group_concat(followed_perc SEPARATOR '_') AS
follow_percentages
...
GROUP  BY baseT.customer_id
</sql-query>

Noteworthy:

(1) For the <sql-query>, just configure the name and the SQL sentence, simple enough,don't have to set the <return> series.

3. DAO

public CustomerInfo getCustomerInfo(int customerId) {
Query q = currentSession().getNamedQuery("getCustomerInfo");
String sql = q.getQueryString();
SQLQuery sqlQuery = currentSession().createSQLQuery(sql);
sqlQuery.addScalar("customerId", StandardBasicTypes.INTEGER).addScalar("phone", StandardBasicTypes.STRING)
.addScalar("currency", StandardBasicTypes.STRING)
.addScalar("accountType", StandardBasicTypes.STRING)
.addScalar("active", StandardBasicTypes.STRING)
.addScalar("customerType", StandardBasicTypes.STRING)
.addScalar("followBetPercentages", StandardBasicTypes.STRING)
.addScalar("balance", StandardBasicTypes.DOUBLE);
sqlQuery.setInteger("customerId", customerId);
sqlQuery.setResultTransformer(Transformers.aliasToBean(CustomerInfo.class));
return (CustomerInfo)sqlQuery.uniqueResult();
}

Noteworthy:

(1) This DAO is the most error-prone part of this example due to inadequate official documentation and lack of online resource. Just feel it!

4. VO

public class CustomerInfo {
private int customerId;
private String accountType;
private String currency;
private String active;
private String customerType;
private String followBetPercentages;
private String phone;
private double balance; //setters and getters...}

5. Integration Test with JUnit4

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath*:applicationContext-persistence.xml")
@ActiveProfiles("test")
public class NamedQueriesDaoTest {

@Autowired
private INamedQueriesDao namedQueriesDao;

/**
* Beware this is an integration test.
*/
//@Ignore
@Test
public void testGetCustomerInfo() {
CustomerInfo customerInfo = namedQueriesDao.getCustomerInfo(2);
assertEquals(2, customerInfo.getCustomerId());
}
}