选择查询的 H2 数据库问题 - 结果错误

Question

我的 h2 数据库有一个非常奇怪的行为，对特定数据库表进行了简单的选择查询。同样的查询适用于 MySQL，但是如果我将应用程序的底层 DB 切换到 H2，它会返回错误的结果（应用程序既可以在 MySQL 上运行，也可以在 H2 DB 上运行）。

我有第二个几乎相同的查询，它工作正常，所以我在这里发布以更好地理解。

有两个表：“StudyProtocolNames”和“StudyRfCoils”，它们与“StudyDetails”表有 N-1 关系（StudyDetails.stId 主键是 StudyProtocolNames 和 StudyRfCoils 的外键）。

这里是父表类“StudyDetails”：

@Entity
@Table(name="StudyDetails", 
uniqueConstraints = @UniqueConstraint(columnNames = "StudyInstanceUID"))
public class StudyDetails implements Serializable {  

    @Id
    @GeneratedValue(strategy = IDENTITY)
    @Column(name="StId", unique = true, nullable = false)
    private Long stId;

    @Column(name="StudyInstanceUID", unique=true, nullable = false)
    private String studyInstanceUID;

    @Column(name="SoapResponse")
    private int soapResponse;

    @Column(name="PatientName")
    private String patientName;

    @Column(name="RfCoil", nullable = false)
    private String rfCoil;

    @Column(name="ProtocolName", nullable = false)
    private String protocolName;

    ...

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "studyDetails", cascade = CascadeType.ALL)
private Set<StudyProtocolNames> studyProtocolNames = new HashSet<>(0);

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "studyDetails", cascade = CascadeType.ALL)
private Set<StudyRfCoils> studyRfCoils = new HashSet<>(0);
    ...
}

这里是“StudyProtocolNames”和“StudyRfCoils”类：

@Entity 
@Table(name="StudyProtocolNames")
public class StudyProtocolNames implements Serializable {

    private static long serialVersionUID = -298254562330274106L;

    @Id
    @GeneratedValue(strategy = IDENTITY)
    @Column(name = "PnId", unique = true, nullable = false)
    private Long pnId;


    @Column(name="StudyInstanceUID")
    private String studyInstanceUID;

    @Column(name="ProtocolName", nullable = false)
    private String protocolName;

    @ManyToOne
    @JoinColumn(name = "StId", referencedColumnName="StId")
    private StudyDetails studyDetails;
    ...
}

...

@Entity 
@Table(name="StudyRfCoils")
public class StudyRfCoils implements Serializable {

    private static long serialVersionUID = -298254562330274106L;

    @Id
    @GeneratedValue(strategy = IDENTITY)
    @Column(name = "RfcId", unique = true, nullable = false)
    private Long rfcId;

    @Column(name="StudyInstanceUID")
    private String studyInstanceUID;

    @Column(name="RfCoil", nullable = false)
    private String rfCoil;

    @ManyToOne
    @JoinColumn(name = "StId", referencedColumnName="StId")
    private StudyDetails studyDetails;
    ...
}

在我的应用程序的某个点，在向“StudyProtocolNames”插入新记录之前，我检查是否已经存在具有相同 studyInstanceUID 和协议名称的记录。如果已经有这样的记录，这个方法返回true。

@Override
public Boolean checkDicomStudyProtocolNameExistForStudy(String studyInstanceUID, String protocolName) {

    Boolean status = false;

    List<String> results=new ArrayList<>();
    Session s=HibernateUtil.openSession();
    s.beginTransaction();
    String hql = "FROM StudyProtocolNames E WHERE E.studyInstanceUID = :studyInstanceUID AND E.protocolName = :protocolName";
    Query query = s.createQuery(hql);
    query.setParameter("protocolName", protocolName.trim());
    query.setParameter("studyInstanceUID", studyInstanceUID);
    results = query.list();
    s.getTransaction().commit();
    s.close();
    log.info(results.size() + " Records found for study in checkDicomStudyProtocolNameExistForStudy: " + studyInstanceUID + " and protocolName" + protocolName);
    if(results.isEmpty()) {
        status = false;
    } else {
        status = true;
    }

    return status;
}

我正在对“StudyRfCoils”表进行完全相同的检查（不同的列相同的逻辑）：

@Override
public Boolean checkDicomStudyRfCoilExistForStudy(String studyInstanceUID, String rfCoil) {

    Boolean status = false;

    List<String> results=new ArrayList<>();
    Session s=HibernateUtil.openSession();
    s.beginTransaction();
    String hql = "FROM StudyRfCoils E WHERE E.studyInstanceUID = :studyInstanceUID AND E.rfCoil = :rfCoil";
    Query query = s.createQuery(hql);
    query.setParameter("rfCoil", rfCoil.trim());
    query.setParameter("studyInstanceUID", studyInstanceUID);
    results = query.list();
    s.getTransaction().commit();
    s.close();
    log.info(results.size() + " Records found for study in checkDicomStudyRfCoilExistForStudy: " + studyInstanceUID + " and rfCoil: " + rfCoil);
    if(results.isEmpty()) {
        status = false;
    } else {
        status = true;
    }

    return status;

}

表 StudyProtocolNames 的第一个检查查询工作正常，如果记录具有相同的“studyInstanceUID”和“protocolName”，则返回 true。

然而，第二个查询总是返回 FALSE。它无法找到具有相同“studyInstanceUID”和“rfCoil”的现有记录。所以我在我的数据库表中结束，其中有多条记录，列“studyInstanceUID”和“rfCoil”具有相同的值：

另一个奇怪的事实是，当我切换到 MySQL 时，第二个检查查询工作正常。这种奇怪的行为只有在使用 H2 DB 时才会发生。

Answer 1

似乎这种行为是由我对 rfCoil 字符串值执行的 trim() 引起的：

@Override
public Boolean checkDicomStudyRfCoilExistForStudy(String studyInstanceUID, String rfCoil) {
    ...
    query.setParameter("rfCoil", rfCoil.trim());
    ...

然而在 MySQL 中这并没有发生