java - 使用 JPA 保留 1 列表

Question

我有一个只有一列的表格。这是一个ID

如何使用 JPA 持久化它？

我试过 entityManager.persist(new OneColumnTable());

并抛出 PersistenceException

Caused by: javax.persistence.PersistenceException: Exception [EclipseLink-6023] (Eclipse Persistence Services - 2.2.0.v20110202-r8913): org.eclipse.persistence.exceptions.QueryException
Exception Description: **The list of fields to insert into the table [DatabaseTable(OneColumnTable)] is empty.  You must define at least one mapping for this table.**
    at org.eclipse.persistence.internal.jpa.EntityManagerImpl.flush(EntityManagerImpl.java:747)
    at com.sun.enterprise.container.common.impl.EntityManagerWrapper.flush(EntityManagerWrapper.java:418)

我该怎么做？

更新

@Entity
@Table(name = "OneColumnTable")
public class OneColumnTable implements Serializable{
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name = "OneColumn")
    private Integer oneColumn;

    public OneColumnTable() {

    }

    public Integer getOneColumn() {
        return oneColumn;
    }

    public void setOneColumn(Integer oneColumn) {
        this.oneColumn= oneColumn;
    }

}

表格

USE [myDB]
GO
/****** Object:  Table [dbo].[OneColumnTable]    Script Date: 07/15/2011 12:10:56 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[OneColumnTable](
    [OneColumn] [bigint] IDENTITY(1,1) NOT NULL,
PRIMARY KEY CLUSTERED 
(
    [OneColumn] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

Answer 1

DataNucleus 可以很好地保存该类。对于某些 RDBMS，当没有指定列时，INSERT 语句必须是特定类型(因为您的唯一列是在数据存储中生成的)，这大概是它不能做的。在 SQLServer 的情况下，任何体面的 JPA 实现都应该生成的语句是“INSERT INTO {tbl} DEFAULT VALUES”。也许得到一个执行该操作的实现？