如何使用Criteria在不同列上连接三个表

Question

上面的快照显示了关系，因为我需要使用Criteria。 我有三个表是内容（Id - PK，标题），文章（Id - PK，articleId，sectionId）部分（Id - PK，标题）。 在数据库中没有使用外键概念。

---

Content.java

@Entity
@Table(name="content")
public class Content{
  private int id;       //PK
  private String title;
  private Set<Article> article;
  @Id
  @GeneratedValue(strategy=GenerationType.AUTO)
  @Column(name="id")
  public int getId(){
      return id;
  }      
  public void setId(int id){
      this.id = id;
  }
  @Column(name="title")
  public String getTitle(){
      return title;
  }
  public void setTitle(String title){
      this.title = title;
  }
  @OneToMany(fetch=FetchType.LAZY)
  @JoinColumn(name="articleId")
  public Set<Article> getArticle(){
      return article;
  }
  public void setArticle(Set<Article> article){
      this.article=article;
  }
}

---

Article.java

@Entity
@Table(name="article")
public class Article{
  private int id;       //PK
  private int articleId;
  private int sectionId;
  private Set<Section> section;
  @Id
  @GeneratedValue(strategy=GenerationType.AUTO)
  @Column(name="id")
  public int getId(){
      return id;
  }      
  public void setId(int id){
      this.id = id;
  }
  @Column(name="articleId")
  public int getArticleId(){
      return articleId;
  }
  public void setArticleId(int articleId){
      this.articleId = articleId;
  }
  @Column(name="sectionId")
  public int getSectionId(){
      return sectionId;
  }
  public void setSectionId(int sectionId){
      this.sectionId = sectionId;
  }
  @OneToMany(fetch=FetchType.LAZY)
  @JoinColumn(name="id")
  public Set<Section> getSection(){
      return section;
  }
  public void setSection(Set<Section> section){
      this.section = section;
  }
}

我在这里使用Criteria加入Content，Article＆amp;基于这些列使用标准的部分是

Criteria content = session.createCriteria(Content.class,"con");
con.createAlias("con.article", "ar");
con.createAlias("ar.section", "sec");
content.list();

这就是我得到的结果：

  

SELECT * FROM Content con inner join Article ar on con.id = ar.articleId INNER JOIN Section sec ON ar.id = sec.id

哪个不正确，如果我将其与预期的SQL查询匹配为：

预期的SQL查询应采用此格式

  

SELECT * FROM Content con，Article ar，Section sec WHERE con.id = ar.articleId AND ar.sectionId = sec.id

任何人都可以帮我解决这个问题，如何使用Criteria作为相同的预期SQL查询来实现结果。

Answer 1

// Firstly,you need entity to your Pojo like this:
// In Article, add a field: private Content content,support Getter and Setter for it
// In Section, add a field: private Article article,also Getter and Setter

// there have three Entity:content,article,section

// Create a DetachedCriteria for Section
DetachedCriteria sectionCriteria = DetachedCriteria
            .forClass(Section.class);

// Create a SubDetachedCriteria for Article InnerJoin Section
// the article is Section's field
DetachedCriteria articleCriteria = sectionCriteria .createCriteria("article",       DetachedCriteria.INNER_JOIN);

// Add join Restriction
// id is article's identity
// for this SQL:INNER JOIN Section sec ON ar.id=sec.id
articleCriteria.add(Restrictions.eq("id",section.id));

// Create a SubDetachedCriteria for Content InnerJoin Article
DetachedCriteria contentCriteria = articleCriteria.createCriteria("content",       DetachedCriteria.INNER_JOIN);

 // Add join Restriction
 // for this SQL:inner join Article ar on con.id=ar.articleId
contentCriteria.add(Restrictions.eq("id",article.articleId));

 // finally,after you finish the join,use the sectionCriteria to execute the CriteriaQuery

我希望它可以帮到你，因为我在我的项目中使用过它