使用Hibernate条件连接不同列上的三个实体所需的帮助

Question

我有三张桌子

Section (id, title, url)//id is Primary key
Category (id, title)//id is Primary key
SubCategory (id, title)//id is Primary key

在这里，我想像简单查询一样连接这些表

Select * From Category cat, Section se, SubCategory subCat  WHERE
 subCat.id=23456  AND subCat.category=cat.id  AND subCat.section = se.id

我的实体文件为：

@Entity
@Table(name="section")
public class SectionEntity{
  private int id;
  private String title;
  //Getter & setter method
}

@Entity
@Table(name="category")
public class CategoryEntity{
  private int id;
  private String title;
  private Set<SubCategoryEntity> subCategory;
  //Getter & setter method
  @OneToMany(cascade = CascadeType.ALL, fetch=FetchType.LAZY)
  @JoinColumn(name="category", insertable=false, updatable=false)
  public Set<SubCategoryEntity> getSubCategory(){
    return this.subCategory;
  }
}

@Entity
@Table(name="subcategory")
public class SubCategoryEntity{
  private int id;
  private String title;

  private Set<SectionEntity> sectionEntity;

  //Getter & setter method
  @OneToMany(fetch=FetchType.LAZY)
  @JoinColumn(name="id", insertable=false, updatable=false)
  public Set<SectionEntity> getSectionEntity(){
    this.section;
  }
}

步骤1：创建类别实体条件categoriesCriteria=Session.CreateCriteria（CategoriesEntity.Class,“CategoryEntity”）；

步骤2：创建SubCategoryEntity和SectionEntity CategoriesCriteria.createAlias的别名（“CategoryEntity.SubCategoryEntity”、“SubCatentity”）；CategoriesCriteria.CreateAlias（“SubcatEntity.SectionsEntity”,“SubcatSectionEntity”）；

步骤3：在投影列表中设置属性

步骤4：将限制添加为：CategoriesCriteria.Add（restrictions.eq（“subCatentity.id”，primCategoryId））；

步骤5：将projection属性设置为CategoryEntity条件CategoriesCriteria.SetProjection（ProjectProplist）；

select this_.id as y0_, this_.title as y1_, this_.sef_url as y2_, subcatenti1_.id as y3_, subcatenti1_.title as y4_, subcatenti1_.sef_url as y5_
from jos_categories this_
inner join jos_subcategories subcatenti1_ on this_.id=subcatenti1_.category
inner join jos_sections subcatsect2_ on subcatenti1_.id=subcatsect2_.id
where subcatenti1_.id=?

select this_.id as y0_, this_.title as y1_, this_.sef_url as y2_, subcatenti1_.id as y3_, subcatenti1_.title as y4_, subcatenti1_.sef_url as y5_
from jos_categories this_
inner join jos_subcategories subcatenti1_ on this_.id=subcatenti1_.category
inner join jos_sections subcatsect2_ on subcatenti1_.section=subcatsect2_.id
where subcatenti1_.id=?

我怎样才能做到这一点，有人能帮我吗？

Answer 1

在SubCategoryFile中进行如下更改,

1）删除“private int section；”及其所有getter和setter方法。

2）并使用此

       @JoinColumn(name="section", insertable=false, updatable=false)
       public Set<SectionEntity> getSection(){
          this.section;
           }

然后试着跑。我希望它能奏效