Hibernate order by Id of child table - mysql

Question

I have two tables as follows:
//TmCategory table
public class TmCategory implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private Long id;
#Column(name="CATEGORY_NAME")
private String categoryName;
#Column(name="OWNER_ID")
private BigInteger ownerId;
//bi-directional many-to-one association to TmCategoryRate
#OneToMany(mappedBy="tmCategory", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
#javax.persistence.OrderBy("startDate ASC")
private Set<TmCategoryRate> tmCategoryRates;
//getters and setters
}
//TmCategoryRates Table
#Entity
#Table(name="tm_category_rates")
public class TmCategoryRate implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private Long id;
#Column(name="CREATED_BY")
private BigInteger createdBy;
#Column(name="CREATED_DATE")
private Timestamp createdDate;
#Column(name="END_DATE")
private Timestamp endDate;
#Column(name="RATE")
private Double rate;
#Column(name="RATE_TYPE")
private String rateType;
#Column(name="START_DATE")
private Timestamp startDate;
//bi-directional many-to-one association to TmCategory
#ManyToOne
#JoinColumn(name="CATEGORY_ID")
private TmCategory tmCategory;
//getters and setters.....
}
And here is the detached criteria am using to get the categories
DetachedCriteria criteria = DetachedCriteria.forClass(TmCategory.class);
criteria.add(Restrictions.eq("id", catId));
DetachedCriteria criteria1 =criteria.createCriteria("tmCategoryRates");
criteria1.addOrder(Order.asc("id"));
List<TmCategory> categories = getHibernateTemplate().findByCriteria(criteria);
Here I am trying to sort the tmCategoryRates in ascending order of their ID.
I am able to get category if there is at least one tmCategoryRates is available for this category. If there is no tmCategoryRates available then its returning null instead of returning category with tmCategoryRates.

Answer 1

If there may be no rates for the category you need a left join. It is not clear why you are using DetachedCriteria here, but see this example from the Hibernate docs
List cats = session.createCriteria( Cat.class )
.createAlias("mate", "mt",
Criteria.LEFT_JOIN,Restrictions.like("mt.name", "good%") )
.addOrder(Order.asc("mt.age"))
.list();
Hibernate 3.5 -- 16.4 Associations