Question

我在两个实体之间存在双向关系：Item（15条记录）和maintenanceContract（22条记录）

映射表item_maintenanceContract链接这两个实体包含25条记录

我想计算maintenanceContract表中的记录，然后运行以下查询：

“SELECT count（*）FROM MaintenanceContract mc LEFT JOIN mc.items as i”

不幸的是，我想象的是25而不是想要的22。我不能简单地依靠MaintenanceContract，因为当我根据项目属性执行相同的搜索时，需要使用Item连接。

我尝试了其他组合：LEFT JOIN，左外连接，右连接......结果没有变化

我缺少什么？

我的项目定义：

@Entity
@Table(name = "item"})
@Inheritance(strategy = InheritanceType.JOINED)
public class Item extends BaseEntity implements Serializable {

  private Long id;
  private Set<MaintenanceContract> maintenanceContracts = new HashSet<MaintenanceContract>(0);

  @Id
  @GeneratedValue(strategy = IDENTITY)

  @Column(name = "id", unique = true, nullable = false)
  public Long getId() {
    return this.id;
  }

  public void setId(Long id) {
    this.id = id;
  }

  @ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
  @JoinTable(name = "item_maintenancecontract", joinColumns = {
      @JoinColumn(name = "item_id", nullable = false, updatable = false)},
      inverseJoinColumns = {@JoinColumn(name = "maintenancecontract_id",
          nullable = false, updatable = false)})

  public Set<MaintenanceContract> getMaintenanceContracts() {
    return maintenanceContracts;
  }

  public void setMaintenanceContracts(Set<MaintenanceContract> maintenanceContracts) {
    this.maintenanceContracts = maintenanceContracts;
  }

}

和我的MaintenanceContract

@Entity
public class MaintenanceContract implements Serializable {

  private Long id;
  private Set<Item> items = new HashSet<Item>(0);

  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  public Long getId() {
    return id;
  }

  public void setId(Long id) {
    this.id = id;
  }

  @ManyToMany(fetch = FetchType.EAGER, mappedBy = "maintenanceContracts")
  public Set<Item> getItems() {
    return this.items;
  }

  public void setItems(Set<Item> items) {
    this.items = items;
  }

}

manyToMany hibernate映射的计数不正确

0 个答案: