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EclipseLink 在使用生成的主键持久保存到表中时，似乎错误地将空主键值传递给 Derby。在这种情况下，Derby 返回尝试修改标识列的错误。Derby 需要一个排除 id 值的 SQL 语句。我的问题是如何强制 EclipseLink 发送正确的 SQL？详情如下...

我正在使用 Eclipselink 映射到最新的 Netbeans 7.3beta2 下的 Derby 数据库 (v10.8.1.2)。

数据库表主键是自动生成的：

CREATE TABLE STUDENT_BATCH ( 
    ID bigint PRIMARY KEY
        GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1),
    FILENAME varchar(200) NOT NULL,
    SCHOOLBOARD varchar(100) NOT NULL,
    CREATE_TS timestamp NOT NULL,
    CONTACT_INFO varchar(200),
    NOTES varchar(2000),
    BOARD_NAME varchar(100)
)
;

对应的jpa类指定id是使用identity的策略生成的：

@Entity
@Table(name = "STUDENT_BATCH")
@XmlRootElement
@NamedQueries({
@NamedQuery(name = "StudentBatch.findAll", query = "SELECT s FROM StudentBatch s")})
public class StudentBatch implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "ID")
    private Long id;
    @Basic(optional = false)
    @Column(name = "FILENAME")
    private String filename;
    @Basic(optional = false)
    @Column(name = "SCHOOLBOARD")
    private String schoolboard;
    @Basic(optional = false)
    @Column(name = "CREATE_TS")
    @Temporal(TemporalType.TIMESTAMP)
    private Date createTs;
    @Column(name = "CONTACT_INFO")
    private String contactInfo;
    @Column(name = "NOTES")
    private String notes;
    @Column(name = "BOARD_NAME")
    private String boardName;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "studentBatchId")
    private Collection<StudentRecord> studentRecordCollection;

    methods etc follow...

当我去持久化课程时，我没有指定 id，以便 Derby 将提供 id。

                StudentBatch sb = new StudentBatch();
                sb.setBoardName(meta.get("BOARD NAME"));
                sb.setContactInfo(meta.get("CONTACT INFO"));
                sb.setCreateTs(new Date());
                sb.setFilename(event.getFile().getFileName());
                sb.setNotes(meta.get("NOTES"));
                sb.setSchoolboard(meta.get("SCHOOL BOARD"));
                _logger.debug("persisting batch");
                em.persist(sb);
                _logger.debug("flushing");
                em.flush();
                _logger.debug("flushed");

然而，Eclipselink 将 id 作为 null 传递给 derby，并且 Derby 给出错误Attempt to modify an identity column：

INFO: DEBUG  11710 27 Nov 2012 18:17:10,558 [http-thread-pool-8080(4)] (FileUploadController.java:75) - persisting batch
INFO: DEBUG  11713 27 Nov 2012 18:17:10,561 [http-thread-pool-8080(4)] (FileUploadController.java:77) - flushing
WARNING: Local Exception Stack: 
Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.3.2.v20111125-r10461): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: java.sql.SQLSyntaxErrorException: Attempt to modify an identity column 'ID'. 
Error Code: -1
Call: INSERT INTO STUDENT_BATCH (ID, BOARD_NAME, CONTACT_INFO, CREATE_TS, FILENAME, NOTES, SCHOOLBOARD) VALUES (?, ?, ?, ?, ?, ?, ?)
bind => [7 parameters bound]
Query: InsertObjectQuery(ca.ontario.mhltc.studentupload.model.StudentBatch[ id=null ])
at org.eclipse.persistence.exceptions.DatabaseException.sqlException(DatabaseException.java:333)

这对我来说很有意义，因为如果我尝试在指定 id 字段的 sql 命令行上执行插入，我也会收到错误消息。

INSERT INTO STUDENT_BATCH (id, BOARD_NAME, CONTACT_INFO, CREATE_TS, FILENAME, NOTES, SCHOOLBOARD)
VALUES (null, 'abc', 'def', current_timestamp, 'aaa', 'aabb', '1234');

给了我这个：

Error code -1, SQL state 42Z23: Attempt to modify an identity column 'ID'. 
Line 1, column 1

Execution finished after 0 s, 1 error(s) occurred.

但是，此插入语句是成功的：

INSERT INTO STUDENT_BATCH (BOARD_NAME, CONTACT_INFO, CREATE_TS, FILENAME, NOTES, SCHOOLBOARD)
VALUES ('abc', 'def', current_timestamp, 'aaa', 'aabb', '1234');

返回

Executed successfully in 0.002 s, 1 rows affected.
Line 1, column 1

Execution finished after 0.002 s, 0 error(s) occurred.

在我看来，Eclipselink 应该知道 Derby 如何处理标识列，并且根本不应该在插入语句中传递 id 列。是否有解决方法，或者我应该转储 Derby 并使用其他数据库？

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1 回答 1

4

EclipseLink 没有在 Derby IDENTITY 的 INSERT 中包含 Id，因此您会遇到一些奇怪的事情。

您之前是否使用过另一种生成器策略并且没有正确重新编译/部署您的代码？

还可以尝试使用 persistence.xml 中的“eclipselink.target-database”="Derby" 设置您的平台。

于 2012-11-28T14:47:14.657 回答