Joining two table entities in Spring Data JPA

Question

I want to write a query like SELECT   FROM Release date type a LEFT JOIN cache media b on a id b id  I am new to Spring Data JPA  I don t know how to write entities for Join query  Here is an attempt    Entity  Table name    Release date type   public class ReleaseDateType         Id      GeneratedValue strategy GenerationType TABLE      private Integer release date type id                  Column nullable   true       private Integer media Id         with getters and setters        Another entity is     Entity  Table name    Cache Media   public class CacheMedia         Id      GeneratedValue strategy GenerationType TABLE      private Integer id                 private Date loadDate    with the getter and setter        I want to write a crudRepository interface such as   public interface ReleaseDateTypeRepository extends CrudRepository lt ReleaseDateType  Long gt        Query  SELECT   FROM Release date type a LEFT JOIN cache media b on a id b id       public List lt ReleaseDateType gt  FindAllWithDescriptionQuery

User · Answer

This has been an old question but solution is very simple to that  If you are ever unsure about how to write criterias  joins etc in hibernate then best way is using native queries  This doesn t slow the performance and very useful   Eq  below       Query nativeQuery   true  value    your sql query   returnTypeOfMethod methodName arg1  arg2

User · Answer

For a typical example of employees owning one or more phones  see this wikibook section   For your specific example  if you want to do a one-to-one relationship  you should change the next code in ReleaseDateType model    Column nullable   true   private Integer media Id    for    OneToOne fetch   FetchType LAZY   JoinColumn name  CACHE MEDIA ID   nullable true  private CacheMedia cacheMedia     and in CacheMedia model you need to add    OneToOne cascade ALL  mappedBy  ReleaseDateType   private ReleaseDateType releaseDateType    then in your repository you should replace    Query  Select   from A a  left join B b on a id b id   public List lt ReleaseDateType gt  FindAllWithDescriptionQuery      by     In this case a query annotation is not need since spring constructs the query from the method name public List lt ReleaseDateType gt  findByCacheMedia Id Integer id      or by    Query  FROM ReleaseDateType AS rdt WHERE cm rdt cacheMedia id    1        This is using a named query method public List lt ReleaseDateType gt  FindAllWithDescriptionQuery Integer id     Or if you prefer to do a  OneToMany and  ManyToOne relation  you should change the next code in ReleaseDateType model    Column nullable   true   private Integer media Id    for    OneToMany cascade ALL  mappedBy  ReleaseDateType   private List lt CacheMedia gt  cacheMedias     and in CacheMedia model you need to add    ManyToOne fetch   FetchType LAZY   JoinColumn name  RELEASE DATE TYPE ID   nullable true  private ReleaseDateType releaseDateType    then in your repository you should replace    Query  Select   from A a  left join B b on a id b id   public List lt ReleaseDateType gt  FindAllWithDescriptionQuery      by     In this case a query annotation is not need since spring constructs the query from the method name public List lt ReleaseDateType gt  findByCacheMedias Id Integer id      or by    Query  FROM ReleaseDateType AS rdt LEFT JOIN rdt cacheMedias AS cm WHERE cm id    1        This is using a named query method public List lt ReleaseDateType gt  FindAllWithDescriptionQuery Integer id

User · Answer

Query  SELECT rd FROM ReleaseDateType rd  CacheMedia cm WHERE

[spring] Joining two table entities in Spring Data JPA

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