如何为HQL编写查询？

我有一个项目：监控学生的成绩。我有一些实体。主要有：如何为HQL编写查询？

@Entity 
@Table(name = "clazzes") 
public class Clazz extends BaseEntity{ 

    @NotEmpty 
    @Column(name = "number") 
    private String number; 

    @NotEmpty 
    @Column(name = "letter") 
    private String letter; 

    @JsonIgnore 
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "clazz", fetch = FetchType.EAGER) 
    private Set<Student> students; 

    @ManyToOne(fetch=FetchType.EAGER) 
    @JoinColumn(name="school_id") 
    private School school; 

    // getters and setters 
} 

@Entity 
@Table(name = "students") 
public class Student extends Person { 

    @JsonIgnore 
    @ManyToMany(fetch = FetchType.EAGER) 
    @JoinTable(name = "parents_students", joinColumns = @JoinColumn(name = "student_id"), 
      inverseJoinColumns = @JoinColumn(name = "parent_id")) 
    private List<Parent> parents; 

    @NotNull 
    @JsonIgnore 
    @ManyToOne 
    @JoinColumn(name = "clazz_id") 
    private Clazz clazz; 

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "student", fetch = FetchType.EAGER) 
    private Set<Grade> grades; 

    // getters and setters 
} 


@Entity 
@Table(name = "grades") 
public class Grade extends BaseEntity{ 

    @ManyToOne(fetch=FetchType.EAGER) 
    @JoinColumn(name = "shedule_id") 
    private Shedule shedule; 

    @NotNull 
    @JsonIgnore 
    @ManyToOne(fetch=FetchType.EAGER) 
    @JoinColumn(name="student_id") 
    private Student student; 

    @Column(name = "task") 
    private String task; 

    @Column(name = "mark") 
    private Integer mark; 

    // getters and setters 
} 


@Entity 
@Table(name = "shedule") 
public class Shedule extends BaseEntity implements Comparable<Shedule>{ 

    @NotNull 
    @Column(name = "date") 
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "dd.MM.yyyy") 
    @DateTimeFormat(pattern = "dd.MM.yyyy") 
    private Date date; 

    @NotNull 
    @ManyToOne(fetch=FetchType.EAGER) 
    @JoinColumn(name="period_id") 
    private Period period; 

    @NotNull 
    @ManyToOne(fetch=FetchType.EAGER) 
    @JoinColumn(name="subject_id") 
    private Subject subject; 

    @NotNull 
    @ManyToOne(fetch=FetchType.EAGER) 
    @JoinColumn(name="clazz_id") 
    private Clazz clazz; 

    @NotNull 
    @ManyToOne(fetch=FetchType.EAGER) 
    @JoinColumn(name="teacher_id") 
    private Teacher teacher; 

    @Column(name = "job") 
    private String job; 

    @JsonIgnore 
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "shedule", fetch = FetchType.EAGER) 
    private Set<Grade> grades; 

    // getters and setters 
}

请告诉我怎么去HQL查询以下数据： Shedule，学生，等级。

我试图写这样的查询：

Query query = this.em.createQuery("SELECT DISTINCT shedule, students, grade " + 
       "FROM Shedule shedule " + 
       "INNER JOIN shedule.clazz clazz " + 
       "INNER JOIN clazz.students students " + 
       "LEFT JOIN students.grades grade with (grade.shedule.id = shedule.id)");

，但我得到由于额外条件 “与（grade.shedule.id = shedule.id）” 以下错误：

java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: with-clause referenced two different from-clause elements [SELECT DISTINCT shedule, students, grade FROM com.vizaco.onlinecontrol.model.Shedule shedule INNER JOIN shedule.clazz clazz INNER JOIN clazz.students students LEFT JOIN students.grades grade with (grade.shedule.id = shedule.id)

如果使用该项目的体系结构，是否可以编写HQL查询？还是有必要改变项目的架构？还是有必要编写原生查询？

来源

2015-07-19 Igor Vartanian

SELECT DISTINCT shedule, students, grade 
     FROM Shedule shedule 
     INNER JOIN shedule.clazz clazz 
     INNER JOIN clazz.students students 
     LEFT JOIN students.grades grade 
     WHERE grade IS NULL OR grade.shedule.id = shedule.id

来源

2015-07-19 15:46:22

如何为HQL编写查询？

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