Java JPA。如果有两条类似的记录被Java解释为相同（唯一）的，如何从DB中只选择一行

我有这样的情况：我在Hibernate中使用JPA，我想从DB中获取一些数据。 不幸的是，我有两组不同的唯一约束。在我的数据库表中有一个，在我的java实体中有另一个稍有不同。我不能在DB中更改一个，因为我没有访问权限，也不能在java实体中更改一个，因为它可能会在应用程序的其他部分生成错误

在Oracle数据库中，我有表Foo。我有两个相似的记录：

我的Java实体根据参数决定记录是否唯一：

列表项

会计识别号

地点识别码

安装ID

解雇日期

箱号

FOO_ID

附件开始日期

所以，在我基于Foo实体执行hibernate选择查询之后，我将从数据库中只获得一条记录（因为java认为来自db的两个Foo是相同的）

这没关系（我喜欢一个结果），但是我能不能指定这两条记录中的哪一条是我最后得到的？假设在本例中，我希望得到一个活动_标志为“Y”（不是表中的第一个，不是随机的，也不是最新的）。这可能吗

现在，我使用@Embeddeble和@IdClass注释在Java代码中设置唯一的参数：

Foo.java类：

@Entity
@Table(name = "Foo")
@IdClass(FooPK.class)

public final class Foo {

   private Long       rowId;
   private Long       boxId;
   private Integer    fooNumber;
   private String     description;
   private BigDecimal upperReadoutDate;
   private BigDecimal upperReadoutDate;
   private String     activityFlag;
   private Long       accId;
   private Long       placeId;
   private Long       installationId;
   private Date       dismountingDate;
   private Date       accStartDate;

   @Id
   @Column(name = "FOO_ID")
   public Integer getFooNumber() {
      return fooNumber;
   }

   public void setFooNumber(Integer mFooNumber) {
      fooNumber = mFooNumber;
   }

   @Column(name = "DESCRIPTION")
   public String getDescription() {
      return description;
   }

   public void setDescription(String mDescription) {
      description = mDescription;
   }

   @Column(name = "D_READ_DATE")
      public BigDecimal getLowerReadoutDate() {
      return lowerReadoutDate;
   }

   public void setLowerReadoutDate(BigDecimal mLowerReadoutDate) {
      lowerReadoutDate = mLowerReadoutDate;
   }

   @Column(name = "U_READ_DATE")
   public BigDecimal getUpperReadoutDate() {
      return upperReadoutDate;
   }

   public void setUpperReadoutDate(BigDecimal mUpperReadoutDate) {
      upperReadoutDate = mUpperReadoutDate;
   }

   @Column(name = "ACTIVITY_FLAG")
   public String getActivityFlag() {
      return activityFlag;
   }

   public void setActivityFlag(String mActivityFlag) {
      activityFlag = mActivityFlag;
   }

   @Id
   @Column(name = "BOX_ID")
   public Long getBoxId() {
      return boxId;
   }

   public void setBoxId(Long mBoxId) {
      boxId = mBoxId;
   }

   @Column(name = "ROW_ID")
   public Long getRowId() {
      return rowId;
   }

   public void setRowId(Long mRowId) {
      rowId = mRowId;
   }

   @Id
   @Column(name = "ACC_ID")
   public Long getAccId() {
      return accId;
   }

   public void setAccId(Long mAccId) {
      accId = mAccId;
   }

   @Id
   @Column(name = "PLACE_ID")
   public Long getPlaceId() {
      return placeId;
   }

   public void setPlaceId(Long mPlaceId) {
      placeId = mPlaceId;
   }

   @Id
   @Column(name = "INSTALLATION_ID")
   public Long getInstallationId() {
      return installationId;
   }

   public void setInstallationId(Long mInstallationId) {
      installationId = mInstallationId;
   }

   @Id
   @Column(name = "DISM_DATE")
   public Date getDismountingDate() {
      return dismountingDate;
   }

   public void setDismountingDate(Date mDismountingDate) {
      dismountingDate = mDismountingDate;
   }

   @Column(name = "ACC_START_DATE")
   public Date getAccStartDate() {
      return accStartDate;
   }

   public void setKuStartDate(Date mKuStartDate) {
      kuStartDate = mKuStartDate;
   }

}

@Embeddable
public class FooPK implements Serializable {

   private static final long serialVersionUID = xxxxxxxxxxxxxxxxxxxL;
   private Long              accId;
   private Long              placeId;
   private Long              installationId;
   private Long              boxId;
   private Integer           fooNumber;
   private Date              dismountingDate;
   private Date              accStartDate;

   @Column(name = "ACC_ID")
   public Long getAccId() {
       return accId;
   }

   public void setAccId(Long mAccId) {
       accId = mAccId;
   }

   @Column(name = "PLACE_ID")
   public Long getPlaceId() {
       return placeId;
   }

   public void setPlaceId(Long mPlaceId) {
       placeId = mPlaceId;
   }

   @Column(name = "INSTALLATION_ID")
   public Long getInstallationId() {
       return installationId;
   }

   public void setInstallationId(Long mInstallationId) {
       installationId = mInstallationId;
   }

   @Column(name = "DISM_DATE")
   public Date getDismountingDate() {
       return dismountingDate;
   }

   public void setDismountingDate(Date mDismountingDate) {
       dismountingDate = mDismountingDate;
   }

   @Column(name = "BOX_ID")
   public Long getBoxId() {
       return boxId;
   }

   public void setBoxId(Long mBoxId) {
       boxId = mBoxId;
   }

   @Column(name = "FOO_ID")
   public Integer getFooNumber() {
       return fooNumber;
   }

   public void setFooNumber(Integer mFooNumber) {
       fooNumber = mFooNumber;
   }

   @Column(name = "ACC_START_DATE")
   public Date getAccStartDate() {
       return accStartDate;
   }

   public void setAccStartDate(Date mAccStartDate) {
       accStartDate = mAccStartDate;
   }

}

FooPK.java类：

@Entity
@Table(name = "Foo")
@IdClass(FooPK.class)

public final class Foo {

   private Long       rowId;
   private Long       boxId;
   private Integer    fooNumber;
   private String     description;
   private BigDecimal upperReadoutDate;
   private BigDecimal upperReadoutDate;
   private String     activityFlag;
   private Long       accId;
   private Long       placeId;
   private Long       installationId;
   private Date       dismountingDate;
   private Date       accStartDate;

   @Id
   @Column(name = "FOO_ID")
   public Integer getFooNumber() {
      return fooNumber;
   }

   public void setFooNumber(Integer mFooNumber) {
      fooNumber = mFooNumber;
   }

   @Column(name = "DESCRIPTION")
   public String getDescription() {
      return description;
   }

   public void setDescription(String mDescription) {
      description = mDescription;
   }

   @Column(name = "D_READ_DATE")
      public BigDecimal getLowerReadoutDate() {
      return lowerReadoutDate;
   }

   public void setLowerReadoutDate(BigDecimal mLowerReadoutDate) {
      lowerReadoutDate = mLowerReadoutDate;
   }

   @Column(name = "U_READ_DATE")
   public BigDecimal getUpperReadoutDate() {
      return upperReadoutDate;
   }

   public void setUpperReadoutDate(BigDecimal mUpperReadoutDate) {
      upperReadoutDate = mUpperReadoutDate;
   }

   @Column(name = "ACTIVITY_FLAG")
   public String getActivityFlag() {
      return activityFlag;
   }

   public void setActivityFlag(String mActivityFlag) {
      activityFlag = mActivityFlag;
   }

   @Id
   @Column(name = "BOX_ID")
   public Long getBoxId() {
      return boxId;
   }

   public void setBoxId(Long mBoxId) {
      boxId = mBoxId;
   }

   @Column(name = "ROW_ID")
   public Long getRowId() {
      return rowId;
   }

   public void setRowId(Long mRowId) {
      rowId = mRowId;
   }

   @Id
   @Column(name = "ACC_ID")
   public Long getAccId() {
      return accId;
   }

   public void setAccId(Long mAccId) {
      accId = mAccId;
   }

   @Id
   @Column(name = "PLACE_ID")
   public Long getPlaceId() {
      return placeId;
   }

   public void setPlaceId(Long mPlaceId) {
      placeId = mPlaceId;
   }

   @Id
   @Column(name = "INSTALLATION_ID")
   public Long getInstallationId() {
      return installationId;
   }

   public void setInstallationId(Long mInstallationId) {
      installationId = mInstallationId;
   }

   @Id
   @Column(name = "DISM_DATE")
   public Date getDismountingDate() {
      return dismountingDate;
   }

   public void setDismountingDate(Date mDismountingDate) {
      dismountingDate = mDismountingDate;
   }

   @Column(name = "ACC_START_DATE")
   public Date getAccStartDate() {
      return accStartDate;
   }

   public void setKuStartDate(Date mKuStartDate) {
      kuStartDate = mKuStartDate;
   }

}

@Embeddable
public class FooPK implements Serializable {

   private static final long serialVersionUID = xxxxxxxxxxxxxxxxxxxL;
   private Long              accId;
   private Long              placeId;
   private Long              installationId;
   private Long              boxId;
   private Integer           fooNumber;
   private Date              dismountingDate;
   private Date              accStartDate;

   @Column(name = "ACC_ID")
   public Long getAccId() {
       return accId;
   }

   public void setAccId(Long mAccId) {
       accId = mAccId;
   }

   @Column(name = "PLACE_ID")
   public Long getPlaceId() {
       return placeId;
   }

   public void setPlaceId(Long mPlaceId) {
       placeId = mPlaceId;
   }

   @Column(name = "INSTALLATION_ID")
   public Long getInstallationId() {
       return installationId;
   }

   public void setInstallationId(Long mInstallationId) {
       installationId = mInstallationId;
   }

   @Column(name = "DISM_DATE")
   public Date getDismountingDate() {
       return dismountingDate;
   }

   public void setDismountingDate(Date mDismountingDate) {
       dismountingDate = mDismountingDate;
   }

   @Column(name = "BOX_ID")
   public Long getBoxId() {
       return boxId;
   }

   public void setBoxId(Long mBoxId) {
       boxId = mBoxId;
   }

   @Column(name = "FOO_ID")
   public Integer getFooNumber() {
       return fooNumber;
   }

   public void setFooNumber(Integer mFooNumber) {
       fooNumber = mFooNumber;
   }

   @Column(name = "ACC_START_DATE")
   public Date getAccStartDate() {
       return accStartDate;
   }

   public void setAccStartDate(Date mAccStartDate) {
       accStartDate = mAccStartDate;
   }

}

---

谢谢你的建议

你真的不应该为一个实体定义一个不唯一的ID

JPA是数据库和对象之间一个非常固执己见的接口，您要么遵循它，要么选择另一种映射/查询技术

更新、删除、插入具有非唯一ID的记录会产生不可预知的结果

如果

ACTIVITY\u标志

是唯一键的一部分，只需将其添加到

@ID

s即可

如果无法将该字段添加为@ID，请将ID自动递增字段添加为表的主键

如果这两种方法都不可行，那么在处理该表时最好使用本机SQL

---

我看到您有一个

ROW\u ID

列作为第一列，如果这是您的主键，只需将其设置为实体的@ID。

如果不将该信息添加到查询中，您需要更改实体。除非您愿意编写直接SQL查询并绕过JPA。您是否尝试过编写命名查询？