我使用Hibernate重写了SpringMVC应用程序。我尝试通过使用SQL查询(在开始使用Hibernate重写之前)进行查询以按组的ID为一组学生选择讲座。 >
"SELECT * FROM lectures WHERE id IN (SELECT lecture_id FROM lectures_groups WHERE group_id =?) ORDER BY date_of_lecture"
我有讲座和小组活动:
@Entity
@Table(name = "lectures")
public class Lecture {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
@ManyToMany(cascade = CascadeType.ALL)
@JoinTable(name = "lectures_groups", joinColumns = @JoinColumn(name = "lecture_id"), inverseJoinColumns = @JoinColumn(name = "group_id"))
private List<Group> groups = new ArrayList<>();
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "teacher_id")
private Teacher teacher;
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "subject_id")
private Subject subject;
@Column(name = "date_of_lecture")
private LocalDateTime date;
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "audience")
private Audience audience;
public Lecture() {
}
//getters setters
}
和:
@Entity
@Table(name = "groups")
public class Group {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
@Column(name = "group_name")
private String name;
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "cathedra_id", referencedColumnName = "id")
private Cathedra cathedra;
@ManyToMany(cascade = CascadeType.ALL)
@JoinTable(name = "lectures_groups", joinColumns = @JoinColumn(name = "group_id"), inverseJoinColumns = @JoinColumn(name = "lecture_id"))
private List<Lecture> lectures = new ArrayList<>();
public Group() {
}
//getters setters
}
我尝试过类似的事情
List<Lecture> lectures = session.createQuery("select l from lectures l join l.groups g where g.id=:groupId")
.setParameter("groupId", group.getId())
.list();
但出现异常:org.hibernate.hql.internal.ast.QuerySyntaxException:讲座未映射 那我该怎么办呢?
答案 0 :(得分:2)
在hql
查询中,您需要在查询中提供entity
的名称,而不是表名。因此,在您的情况下,应在查询中将lectures
替换为Lecture
。
List<Lecture> lectures = session.createQuery("select l from Lecture l join l.groups g where g.id=:groupId")
.setParameter("groupId", group.getId())
.list();