'지침'이라는 엔티티가 있습니다. 때로는 각 지침은 그 전후에 지침을 추적해야합니다. 예를 들어, 기존 명령어 A에서 계속 진행중인 새로운 명령어 B가있는 경우, 명령어 B는 명령어 A가 이전 명령어임을 인식해야하고 명령어 A는 명령어 B가 명령어 B가 그 다음 명령어임을 알고 있어야합니다. 모든 강좌가 강습 전후 강좌를 가질 수있는 것은 아닙니다.JPA : 일대일 + 자기 참조 + 양방향
JPA (EclipseLink)에서 이것을 구현하는 방법 : [일대일 + 자기 참조 + 양방향] 관계?
지금까지 (아직 작동하지 않는) 내가이 함께했다 :
MySQL의 DB :
CREATE TABLE instructions (
instruction_id int(11) NOT NULL AUTO_INCREMENT,
instruction_title varchar(100) NOT NULL,
instruction_text varchar(999) NOT NULL,
instruction_previous_id int(11) DEFAULT NULL,
PRIMARY KEY (instruction_id),
CONSTRAINT instructions_ibfk_3
FOREIGN KEY (instruction_previous_id)
REFERENCES instructions (instruction_id));
엔티티 : 현재
@Entity
@Table(name = "instructions")
public class Instructions implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Basic(optional = false)
@Column(name = "instruction_id")
private Integer instructionId;
@Basic(optional = false)
@Column(name = "instruction_title")
private String instructionTitle;
@Basic(optional = false)
@Column(name = "instruction_text")
private String instructionText;
@JoinColumn(name="instruction_previous_id", referencedColumnName = "instruction_id", nullable = true)
@OneToOne(optional = true)
private Instructions instructionPrevious;
@OneToOne(cascade = CascadeType.ALL, mappedBy = "instructionPrevious")
private Collection<Instructions> instructionNextCollection;
// other properties, setter & getter
}
새 명령을 만들에 아무런 문제가 있었다 읽는 중 오류가 발생했습니다.
Instructions instruction = em.find(Instructions.class, instructionId);
instruction.getInstructionNextCollection().size(); //error this line
Local Exception Stack: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.0.1.v20100213-r6600): org.eclipse.persistence.exceptions.DatabaseException Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 'atiits.instructions_instructions' doesn't exist Error Code: 1146 Call: SELECT t1.instruction_id, t1.instruction_urgent, t1.instruction_uploaded_by, t1.instruction_translate, t1.instruction_title, t1.instruction_type, t1.instruction_translate_received, t1.instruction_is_cancelled, t1.instruction_translate_sent, t1.instruction_had_workorder, t1.instruction_text, t1.instruction_update_date, t1.instruction_update_by, t1.instruction_create_by, t1.instruction_translator, t1.instruction_create_date, t1.instruction_company_id, t1.instruction_previous_id, t1.instruction_status_id FROM instructions_instructions t0, instructions t1 WHERE ((t0.Instructions_instruction_id = ?) AND (t1.instruction_id = t0.instructionNextCollection_instruction_id)) bind => [874] Query: ReadAllQuery(name="instructionNextCollection" referenceClass=Instructions sql="SELECT t1.instruction_id, t1.instruction_urgent, t1.instruction_uploaded_by, t1.instruction_translate, t1.instruction_title, t1.instruction_type, t1.instruction_translate_received, t1.instruction_is_cancelled, t1.instruction_translate_sent, t1.instruction_had_workorder, t1.instruction_text, t1.instruction_update_date, t1.instruction_update_by, t1.instruction_create_by, t1.instruction_translator, t1.instruction_create_date, t1.instruction_company_id, t1.instruction_previous_id, t1.instruction_status_id FROM instructions_instructions t0, instructions t1 WHERE ((t0.Instructions_instruction_id = ?) AND (t1.instruction_id = t0.instructionNextCollection_instruction_id))") at org.eclipse.persistence.exceptions.DatabaseException.sqlException(DatabaseException.java:333) at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.basicExecuteCall(DatabaseAccessor.java:687)
답글을 달려면 http://stackoverflow.com/questions/3393515/jpa-how-to-have-one-to-many-relation-of-the-same-entity-type – perissf