Get data joining two table in room having same column id

Question

Hi I am using two table student and student_address having common column id as uid in both table(that can't be changed in any condition)

I am using class StudentAndAddress as

public class StudentAndAddress{

    @Embedded
    private Student student;

    @Embedded(prefix = "type_")
    private StudentAddress studentAddress;

    public Address getStudent() {
        return student;
    }

    public void setStudent(Student student) {
        this.student = student;
    }

    public StudentAddress getStudentAddress() {
        return studentAddress;
    }

    public void setStudentAddress(StudentAddress studentAddress) {
        this.studentAddress = studentAddress;
    }

}

and query i am using as:

@Query("SELECT * FROM student  INNER JOIN student_address ON student.uid == student_address.address_uid and address_link.linkto_type==:linkToType")
LiveData<List<StudentAndAddress>> getStudentAndAddress(String linkToType);

I am getting value of first table but not getting value of second table. In database both table are there

Answer 1

In room we need to solve this type of queries using relation

public class StudentAndAddress{

    @Embedded
    private StudentAddress studentAddress;


    @Relation(
            parentColumn = "address_uid",
            entityColumn = "uid",
            entity = Student.class
    )
    private Student student;


    public Address getStudent() {
        return student;
    }

    public void setStudent(Student student) {
        this.student = student;
    }

    public StudentAddress getStudentAddress() {
        return studentAddress;
    }

    public void setStudentAddress(StudentAddress studentAddress) {
        this.studentAddress = studentAddress;
    }

}

and query we need to write is:-

@Query("SELECT * FROM student_address WHERE linkto_type==:linkToType")
LiveData<List<StudentAndAddress>> getStudentAndAddress(String linkToType);