在Spring Data JPA中加入两个表实体 [英] Joining two table entities in Spring Data JPA

问题描述

我想写一个类似于 Select *的查询，在a.id = b.id ，
的左边加入b b我是Spring的新手数据JPA。
我不知道如何为Join查询编写实体。

  @Entity 
 @Table name =Release_date_type）
 public class ReleaseDateType {
 
 @Id 
 @GeneratedValue（strategy = GenerationType.TABLE）
 private Integer release_date_type_id; 
 @Column 
私人整数sort_order; 
 @Column 
私有字符串描述; 
 @Column 
 private String data_source_type; 
 @Column（nullable = true）
私人整数media_Id; 
 @Column 
 private String source_system; 
 @Column 
 private String update_Name; 
 @Column 
私人日期update_Date; 
 @Column 
 private String create_Name; 
 @Column 
私人日期create_Date; 
 @Column 
 private Integer version_Id; 
 @Column（nullable = true）
 private整数auto_Firm_Flag; 
 @Column（nullable = true）
 private Integer auto_Firm_Months; 
 @Column（nullable = true）
 private整数auto_Firm_Days; 
 with getters and setters ... 
} 
  

另一个实体是

  @Entity 
 @Table（name =Cache_Media）
 public class CacheMedia {
 
 @Id 
 @GeneratedValue（strategy = GenerationType.TABLE）
 private Integer id; 
 @Column（name =code）
 private String code; 
 @Column（name =POSITION）
私人整数位置; 
 @Column（name =DESCRIPTION）
 private String media_Description; 
 @Column（name =LOAD_DATE）
私人日期loadDate;与getter和setter ..} 
  

我想写一个crudRepository接口。
例如

  public interface ReleaseDateTypeRepository扩展CrudRepository< ReleaseDateType，Long> {
 @Query（Select *来自A a.b = a.id = b.id的左连接B b）b $ b public List< ReleaseDateType> FindAllWithDescriptionQuery（）; 
} 
  

解决方案

要执行一对一关系，您应该更改ReleaseDateType模型中的下一个代码：

  @Column（nullable = true）
 private Integer media_Id; 
  

用于：

  @OneToOne（fetch = FetchType.LAZY）
 @JoinColumn（name =CACHE_MEDIA_ID，nullable = true）
私有CacheMedia cacheMedia; 
  

在CacheMedia模型中，您需要添加：

  @OneToOne（cascade = ALL，mappedBy =ReleaseDateType）
 private ReleaseDateType releaseDateType; 
  

然后在您的存储库中您应该替换：

<
public List< ReleaseDateType> FindAllWithDescriptionQuery（）;

通过：

  //在这种情况下，不需要查询注释，因为spring会从方法名称
构造查询public List< ReleaseDateType> findByCacheMedia_Id（Integer id）; 
  

或者：

  @Query（FROM ReleaseDateType AS rdt WHERE cm.rdt.cacheMedia.id =？1）//这是使用命名查询方法
 public List< ReleaseDateType> FindAllWithDescriptionQuery（Integer id）; 
  

或者如果您喜欢做 @OneToMany 和 @ManyToOne 关系，您应该更改ReleaseDateType模型中的下一个代码：

  @Column（nullable = true）
 private Integer media_Id; 
  

用于：

  @OneToMany（cascade = ALL，mappedBy =ReleaseDateType）
 private List< CacheMedia> cacheMedias; 
  

在CacheMedia模型中，您需要添加：

  @ManyToOne（fetch = FetchType.LAZY）
 @JoinColumn（name =RELEASE_DATE_TYPE_ID，nullable = true）
 private ReleaseDateType releaseDateType; 
  

然后在您的存储库中您应该替换：

<
public List< ReleaseDateType> FindAllWithDescriptionQuery（）;

通过：

  //在这种情况下，不需要查询注释，因为spring会从方法名称
构造查询public List< ReleaseDateType> findByCacheMedias_Id（Integer id）; 
  

或者：

  @Query（FROM ReleaseDateType AS rdt LEFT JOIN rdt.cacheMedias AS cm WHERE cm.id =？1）//这是使用命名查询方法
 public List< ReleaseDateType> FindAllWithDescriptionQuery（Integer id）; 
  

I want to write a query like Select * from A a left join B b on a.id=b.id, I am new to Spring Data JPA. I don't know how to write entities for Join query.

@Entity
@Table(name = "Release_date_type")
public class ReleaseDateType {

    @Id
    @GeneratedValue(strategy=GenerationType.TABLE)
    private Integer release_date_type_id;
    @Column
    private Integer sort_order;
    @Column
    private String description;
    @Column
    private String data_source_type;
    @Column(nullable = true) 
    private Integer media_Id;
    @Column
    private String source_system;
    @Column
    private String update_Name;
    @Column
    private Date update_Date;
    @Column
    private String create_Name;
    @Column
    private Date create_Date;
    @Column
    private Integer version_Id;
    @Column(nullable = true) 
    private Integer auto_Firm_Flag;
    @Column(nullable = true) 
    private Integer auto_Firm_Months;
    @Column(nullable = true) 
    private Integer auto_Firm_Days;
    with getters and setters...
}

Another entity is as

@Entity
@Table(name = "Cache_Media")
public class CacheMedia{

@Id
@GeneratedValue(strategy=GenerationType.TABLE)
private Integer id;
@Column(name="code")
private String code;
@Column(name="POSITION")
private Integer position;
@Column(name="DESCRIPTION")
private String media_Description;
@Column(name="LOAD_DATE")
private Date loadDate; with the getter and setter ..}

I want to write a crudRepository interface. such as

public interface ReleaseDateTypeRepository extends CrudRepository<ReleaseDateType, Long>{
  @Query("Select * from A a  left join B b on a.id=b.id")
public List<ReleaseDateType> FindAllWithDescriptionQuery();
}

解决方案

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<ReleaseDateType> FindAllWithDescriptionQuery();

by:

//In this case a query annotation is not need since spring constructs the query from the method name
public List<ReleaseDateType> 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<ReleaseDateType> 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<CacheMedia> 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<ReleaseDateType> FindAllWithDescriptionQuery();

by:

//In this case a query annotation is not need since spring constructs the query from the method name
public List<ReleaseDateType> 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<ReleaseDateType> FindAllWithDescriptionQuery(Integer id);

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