Spring data JPA have selection of one table 1 get the details of table 2 as well

Question

I have two tables Student and Student_Type, Each student have each type, while selecting student table how to get the details Student_Type in Spring data JPA.

Student Enity

@Enity
@Table(schema="DATA", name="STUDENT")
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class Student {
 @Id
 @GeneratedValue(strategy=GenerationType.IDENTITY)
 private Long id;

 @Column(name="fname")
 private string fanme;

 @Column(name="lname")
 private string lanme;
 
 @Transiant
 private string config_type; // Studen_Type type should be populate on here  
}

Student_Type Enity

@Enity
@Table(schema="DATA", name="STUDENT_TYPE")
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class StudentType {
 @Id
 @GeneratedValue(strategy=GenerationType.IDENTITY)
 private Long id;

 @Column(name="type")
 private string type;

 @Column(name="stud_id") // Student `id` is referenced
 private string stud_id;

 @OneToOne(optional=false)
 @JoinCoulumn(name="stud_id" referencedColumnName= "id" insertable=false, updateble=false)
 private Student student;
}

While doing select query of student table how to get the type from Student_type table.

Sample data of Student table | Id | fname | lname| | --- | ----- |----| | 1 | Raju | Mikel | | 2 | Thomas | George | | 3 | Arun | Nair |

Sample data of Student_Type table | Id | type | stud_id| | --- | ----- |----| | 1 | Performer | 1 | | 2 | Avg | 2 | | 3 | Performer | 3 |

I'm new in Spring data JPA,

I tried the One to One mapping but its not working, This is my native query,

StudentRepository

 @Query("select s.fname, s.lanme, st.type as config_type from student s left join student_type st on s.id=st.stud_id", nativeQuery=true)
List<Student> findStudetType();

Please help that would be appreciated

Answer 1

In your Student, add:

@OneToOne(mappedBy="student")
private StudentType tudentType;

Secondly, change your query to JPQL:

@Query("SELECT s FROM Student s LEFT JOIN FETCH StudentType st")

FYI: https://www.baeldung.com/jpa-joincolumn-vs-mappedby