Java 如何编写多对多关联表的查询

我有两个实体，它们之间有多对多关系。我想在关联表上写一个查询

Here are the two entities. Craftsmen and Skill.
I want to write a query which selects all Craftsmen with a given skill. 

    @Entity
    @Table(name = "craftsman")
    public class Craftsman {

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private Long id;

        @ManyToMany
        @JoinTable(name = "craftman_skill", joinColumns = @JoinColumn(name = "craftman_id", referencedColumnName = "id"), 
            inverseJoinColumns = @JoinColumn(name = "skill_id", referencedColumnName = "id"))
        private List<Skill> skillList;
    }
        @Entity
        @Table(name = "skill")
        public class Skill {
            @ManyToMany(mappedBy = "skillList")
            @JsonBackReference
            private List<Craftsman> craftmanList;
        }

以下是我得到的错误：

Caused by: java.lang.IllegalArgumentException: org.hibernate.QueryException: could not resolve property: skill_id of: com.craftsmen.crafts.persistence.Skill [SELECT c FROM com.craftsmen.crafts.persistence.Craftsman c JOIN c.skillList sl WHERE c.skillList.skill_id = :skillId ]
Caused by: org.hibernate.QueryException: could not resolve property: skill_id of: com.craftsmen.crafts.persistence.Skill [SELECT c FROM com.craftsmen.crafts.persistence.Craftsman c JOIN c.skillList sl WHERE c.skillList.skill_id = :skillId ]

---

我想问题是，您的

技能

实体确实没有技能id，或者更好，没有

id

您是否尝试为您的

技能

实体提供

id

@Entity
@Table(name = "skill")
public class Skill {
   @Id
   @GeneratedValue(strategy = GenerationType.IDENTITY)
   private Long id;

   @ManyToMany(mappedBy = "skillList")
   @JsonBackReference
   private List<Craftsman> craftmanList;
}

然后将

查询

更改为

SELECT c FROM Craftsman c JOIN c.skillList sl WHERE sl.id = :skillId

---

这是应该的。

也可以考虑使用jpRePi蓄选项：

public interface CraftsmanRepository extends JpaRepository<Craftsman, String> {
    public List<Craftsman> getBySkillListIn(@NotEmpty List<Skill> skillList);

---

c.skillList.skill\u id

试图做什么？你已经加入了！为什么不直接做

s1.id

？！！这是JPQL，不是SQL，alsoSkill有一个id，我只是没有发布是偶然的。

@Entity
@Table(name = "craftsman")
public class Craftsman {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @ManyToMany
    @JoinTable(name = "craftman_skill", joinColumns = @JoinColumn(name = "craftman_id", referencedColumnName = "id"), 
        inverseJoinColumns = @JoinColumn(name = "skill_id", referencedColumnName = "id"))
    private List<Skill> skillList;
}

SELECT c FROM Craftsman c JOIN c.skillList sl WHERE sl.id = :skillId

public interface CraftsmanRepository extends JpaRepository<Craftsman, String> {
    public List<Craftsman> getBySkillListIn(@NotEmpty List<Skill> skillList);

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