select stu.studentid,stu.studentname, addr.studentaddress from Student stu left join Address addr where (stu.studentid=addr.studentid);

@Entity
@Table(name = "student")
public class Student implements java.io.Serializable {

   private String studentid;
   private String studentname;
   
         // I declared mapping relations here, is it correct?
   @OneToMany
   @JoinColumn(name="studentid")
   private Address address;
   

   public Student() {
   }

   public Student(String studentid) {
      this.studentid = studentid;
   }

   public Student(String studentid, String studentname) {
      this.studentid = studentid;
      this.studentname = studentname;
   }

   @Id
   @Column(name = "studentid", unique = true, nullable = false)
   public String getStudentid() {
      return this.studentid;
   }

   public void setStudentid(String studentid) {
      this.studentid = studentid;
   }

   @Column(name = "studentname")
   public String getStudentname() {
      return this.studentname;
   }

   public void setStudentname(String studentname) {
      this.studentname = studentname;
   }

   public void setAddress(Address address) {
      this.address = address;
   }

   public Address getAddress() {
      return address;
   }

}

@Entity
@Table(name = "address")
public class Address implements java.io.Serializable {

   private String studentid;
   private String studentaddress;

   public Address() {
   }

   public Address(String studentid) {
      this.studentid = studentid;
   }

   public Address(String studentid, String studentaddress) {
      this.studentid = studentid;
      this.studentaddress = studentaddress;
   }

   @Id
   @Column(name = "studentid", unique = true, nullable = false)
   public String getStudentid() {
      return this.studentid;
   }

   public void setStudentid(String studentid) {
      this.studentid = studentid;
   }

   @Column(name = "studentaddress")
   public String getStudentaddress() {
      return this.studentaddress;
   }

   public void setStudentaddress(String studentaddress) {
      this.studentaddress = studentaddress;
   }

}