I have two tables below:
x
@Entity
@Table(name="COLLEGE")
public class College {
private Long collegeId;
private List<Student> students;
@Id
@Column(name = "COLLEGE_ID")
public Long getCollegeId() {
return this.collegeId;
}
public void setCollegeId(final Long collegeId) {
this.collegeId= collegeId;
}
@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "college")
@Cascade(org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
public List<Student> getStudents() {
if (this.students== null) {
this.students= new ArrayList<>();
}
return this.students;
}
public void setStudents(List<Student> students){
this.students = students
}
}
@Entity
@Table(name="STUDENT")
public class Student {
private Long studentId;
private College college;
private String name;
private String department;
@Id
public Long getStudentId() {
return this.studentId;
}
public void setStudentId(Long studentId) {
this.studentId = studentId;
}
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "COLLEGE_ID")
public getCollege() {
return this.college;
}
public setCollege(College college) {
this.college = college;
}
}
I want to get the college
object with list of students
of a specific department
. The SQL query is below:
select *
from COLLEGE c
inner join STUDENT s on c.COLLEGE_ID= s.collegeId
where c.COLLEGE_ID=12345 and s.DEPARTMENT="ENGINEERING";
So far I have tried the below JPA query but it is returning multiple College
objects.
SELECT DISTINCT c
FROM COLLEGE c
INNER JOIN c.students s
where c.collegeId= :collegeid and s.department = :department
How to return a single college
object with list of students
with filtered department
?
NOTE: I can’t alter the entity objects used here.
Advertisement
Answer
Try to use this query, using JOIN FETCH
instead INNER JOIN
:
SELECT DISTINCT c FROM College c
JOIN FETCH c.students s
WHERE c.collegeId= :collegeid
AND s.department = :department