import java.io.Serializable;

import javax.persistence.Column;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.DiscriminatorType;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.Table;

@Entity
@Table(name = "base", schema = "public")
@Inheritance(strategy = InheritanceType.JOINED)
@DiscriminatorColumn(discriminatorType=DiscriminatorType.STRING, name="dtype")
public class BaseTest implements Serializable {
   private Integer id;

   @Id
   @Column(name = "id", unique = true, nullable = false)
   public Integer getId() {
      return this.id;
   }

   public void setId(Integer id) {
      this.id = id;
   }
}

import javax.persistence.Column;
import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.Table;

@Entity
@Table(name = "dok", schema = "public")
@Inheritance(strategy = InheritanceType.JOINED)
@DiscriminatorValue(value = "dok")
public class Dok extends BaseTest{
   private Integer dokId;

   @Column(name = "dok_id", unique = true, nullable = false)
   public Integer getDokId() {
      return this.dokId;
   }

   public void setDokId(Integer id) {
      this.dokId = id;
   }
}