无法将 MySql 查询（ManyToMany 关系）转换为 HQL答案

【问题标题】：Can't convert MySql Query(ManyToMany relationship) to HQL无法将 MySql 查询（ManyToMany 关系）转换为 HQL
【发布时间】：2023-03-23 17:31:01
【问题描述】：

有 3 个实体：1）问题，2）它们之间的标签和连接表 - Question_Has_Tag

java 中的相同对象，除了连接表。取而代之的是：

public class Question {
  //
  @ManyToMany(fetch = FetchType.LAZY)
  @JoinTable(name = "question_has_tag",
        joinColumns = @JoinColumn(name = "question_id"),
        inverseJoinColumns = @JoinColumn(name = "tag_id"))
  private List<Tag> tags;

public class Tag {
  //
  @ManyToMany(mappedBy = "tags", fetch = FetchType.LAZY)
  @ContainedIn
  private List<Question> questions;

要转换的查询是：

select * from question as q
   join question_has_tag as qht on q.id = qht.question_id
   where qht.question_id in (select question_id from question_has_tag where tag_id = 1);

我对连接表和集合感到困惑。将一个转换成另一个

如果您需要更多代码或信息，请告诉我

【问题讨论】：

标签： mysql sql spring hibernate jpa

【解决方案1】：

试试这个：

@Entity
public class Question {
    @ManyToMany(mappedBy = "question_has_tag", fetch = FetchType.LAZY)
    private List<Tag> tags;
}

@Entity
public class Tag {
    @ManyToMany(targetEntity = Question.class, fetch = FetchType.LAZY)
    private List<Question> questions;
}

以及查询结果的存储库：

@Repository
public interface QuestionRepository extends JpaRepository<Question, Integer> {
  @Query("select q from Question q join Tag t where q.id in (:ids)")
  public List<Question> getQuestionsById(@Param("ids") List<Integer> ids);
}

【讨论】：