我目前正在尝试为工作网络应用设置我的JPA后端。但是，当我尝试执行JPQL查询时，它总是将其转换为大写。
例如SELECT u.firstName FROM User将转换为SELECT FIRSTNAME FROM USER。由于表USER不存在，因此将引发异常。
如果我在mySql数据库中创建名为USER的表，则此问题已解决，但我想知道为什么会这样。
用户实体：
@Entity
@NamedQuery(name="User.findAll", query="SELECT u.firstName FROM User u")
public class User implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private int idUser;
@Lob
private String educationText;
private String email;
private String firstName;
private int isModerator;
@Lob
private String jobExperienceText;
private String lastName;
private String password;
private String phoneNumber;
private String photoUrl;
//bi-directional many-to-one association to Advertisment
@OneToMany(mappedBy="user")
private List<Advertisment> advertisments;
//bi-directional many-to-one association to Article
@OneToMany(mappedBy="user")
private List<Article> articles;
//bi-directional many-to-one association to Connection
@OneToMany(mappedBy="user")
private List<Connection> connections;
//bi-directional many-to-one association to ConnectionRequest
@OneToMany(mappedBy="user")
private List<ConnectionRequest> connectionRequests;
//bi-directional many-to-many association to Conversation
@ManyToMany
@JoinTable(
name="ParticipantsOfConversation"
, joinColumns={
@JoinColumn(name="User_idUser")
}
, inverseJoinColumns={
@JoinColumn(name="Conversation_idConversation")
}
)
private List<Conversation> conversations;
//bi-directional one-to-one association to User_has_Skill
@OneToOne(mappedBy="user")
private User_has_Skill userHasSkill;
public User() {
}
public int getIdUser() {
return this.idUser;
}
public void setIdUser(int idUser) {
this.idUser = idUser;
}
public String getEducationText() {
return this.educationText;
}
public void setEducationText(String educationText) {
this.educationText = educationText;
}
public String getEmail() {
return this.email;
}
public void setEmail(String email) {
this.email = email;
}
public String getFirstName() {
return this.firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public int getIsModerator() {
return this.isModerator;
}
public void setIsModerator(int isModerator) {
this.isModerator = isModerator;
}
public String getJobExperienceText() {
return this.jobExperienceText;
}
public void setJobExperienceText(String jobExperienceText) {
this.jobExperienceText = jobExperienceText;
}
public String getLastName() {
return this.lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getPassword() {
return this.password;
}
public void setPassword(String password) {
this.password = password;
}
public String getPhoneNumber() {
return this.phoneNumber;
}
public void setPhoneNumber(String phoneNumber) {
this.phoneNumber = phoneNumber;
}
public String getPhotoUrl() {
return this.photoUrl;
}
public void setPhotoUrl(String photoUrl) {
this.photoUrl = photoUrl;
}
public List<Advertisment> getAdvertisments() {
return this.advertisments;
}
public void setAdvertisments(List<Advertisment> advertisments) {
this.advertisments = advertisments;
}
public Advertisment addAdvertisment(Advertisment advertisment) {
getAdvertisments().add(advertisment);
advertisment.setUser(this);
return advertisment;
}
public Advertisment removeAdvertisment(Advertisment advertisment) {
getAdvertisments().remove(advertisment);
advertisment.setUser(null);
return advertisment;
}
public List<Article> getArticles() {
return this.articles;
}
public void setArticles(List<Article> articles) {
this.articles = articles;
}
public Article addArticle(Article article) {
getArticles().add(article);
article.setUser(this);
return article;
}
public Article removeArticle(Article article) {
getArticles().remove(article);
article.setUser(null);
return article;
}
public List<Connection> getConnections() {
return this.connections;
}
public void setConnections(List<Connection> connections) {
this.connections = connections;
}
public Connection addConnection(Connection connection) {
getConnections().add(connection);
connection.setUser(this);
return connection;
}
public Connection removeConnection(Connection connection) {
getConnections().remove(connection);
connection.setUser(null);
return connection;
}
public List<ConnectionRequest> getConnectionRequests() {
return this.connectionRequests;
}
public void setConnectionRequests(List<ConnectionRequest> connectionRequests) {
this.connectionRequests = connectionRequests;
}
public ConnectionRequest addConnectionRequest(ConnectionRequest connectionRequest) {
getConnectionRequests().add(connectionRequest);
connectionRequest.setUser(this);
return connectionRequest;
}
public ConnectionRequest removeConnectionRequest(ConnectionRequest connectionRequest) {
getConnectionRequests().remove(connectionRequest);
connectionRequest.setUser(null);
return connectionRequest;
}
public List<Conversation> getConversations() {
return this.conversations;
}
public void setConversations(List<Conversation> conversations) {
this.conversations = conversations;
}
public User_has_Skill getUserHasSkill() {
return this.userHasSkill;
}
public void setUserHasSkill(User_has_Skill userHasSkill) {
this.userHasSkill = userHasSkill;
}
}
Persistnce.xml
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
<persistence-unit name="linkedInProject" transaction-type="RESOURCE_LOCAL">
<class>model.Advertisment</class>
<class>model.AdvertismentPK</class>
<class>model.Advertisment_has_Skill</class>
<class>model.Advertisment_has_SkillPK</class>
<class>model.Application</class>
<class>model.ApplicationPK</class>
<class>model.Article</class>
<class>model.ArticlePK</class>
<class>model.Comment</class>
<class>model.CommentPK</class>
<class>model.Connection</class>
<class>model.ConnectionPK</class>
<class>model.ConnectionRequest</class>
<class>model.ConnectionRequestPK</class>
<class>model.Conversation</class>
<class>model.Interest</class>
<class>model.InterestPK</class>
<class>model.Message</class>
<class>model.MessagePK</class>
<class>model.Skill</class>
<class>model.User</class>
<class>model.User_has_Skill</class>
<properties>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/linkedIn"/>
<property name="javax.persistence.jdbc.user" value="ld"/>
<property name="javax.persistence.jdbc.password" value="---"/>
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
</properties>
</persistence-unit>
</persistence>
我收到的例外情况：
Jul 26, 2018 1:01:49 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [servlets.UserServlet] in context with path [/linkedInProject] threw exception
javax.persistence.PersistenceException: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 'linkedIn.USER' doesn't exist
Error Code: 1146
Call: SELECT FIRSTNAME FROM USER
Query: ReportQuery(name="User.findAll" referenceClass=User sql="SELECT FIRSTNAME FROM USER")
at org.eclipse.persistence.internal.jpa.QueryImpl.getDetailedException(QueryImpl.java:378)
at org.eclipse.persistence.internal.jpa.QueryImpl.executeReadQuery(QueryImpl.java:260)
at org.eclipse.persistence.internal.jpa.QueryImpl.getResultList(QueryImpl.java:469)
at dao.UserDAOImpl.list(UserDAOImpl.java:27)
at servlets.UserServlet.doGet(UserServlet.java:58)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at filters.EntityManagerInterceptor.doFilter(EntityManagerInterceptor.java:41)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:496)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
答案 0 :(得分：0)
您可以使用@Table来注释您的实体类，并将表名包装在背景幕中以使其区分大小写：
@Table(name="`User`")
@Entity
@NamedQuery(name="User.findAll", query="SELECT u.firstName FROM User u")