mysql - com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException : Unknown column in 'field list' using Criteria and mapping annotation

Question

我有访问结果的标准

第一个 Hibernate Dao 是

AnswerText answersText = questionManager.getAnswerTextByAnswerIdAndLanguageId(answers.getAnswerId(), 1L);

@Override
    public AnswerText getAnswerTextByAnswerIdAndLanguageId(Number answerId,Number languageId) {
        Criteria criteria = sessionFactory.getCurrentSession().createCriteria(AnswerText.class);
        criteria.add(Restrictions.eq("answer.answerId", answerId));
        criteria.add(Restrictions.eq("languageId", languageId));
        List<AnswerText> results = criteria.list();
        return (results !=null && !results.isEmpty()? results.get(0): null);
    }




Answers.java

@Entity  
@Table(name = "ANSWERS")
@Cacheable

@JsonIgnoreProperties(ignoreUnknown = true)
public class Answer {

    @Id  
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "ANSWER_ID")  
    private Long  answerId;

    @Column(name = "QUESTION_ID")  
    private Long      questionId;

    @Column(name = "DATE_CREATED")  
    private Timestamp   dateCreated;

    @Column(name = "CREATED_BY_ID")  
    private Long      creatorId;

    @Column(name = "DATE_MODIFIED")  
    private Timestamp   dateModified;

    @Column(name = "MODIFIED_BY_ID")  
    private Long    modifierId;

    @OneToMany(fetch = FetchType.EAGER,mappedBy = "answer" )
    private Set<AnswerText> answerText = new HashSet<AnswerText>();

            //getters and setters


AnswerText.java

@Entity  
@Table(name = "ANSWERTEXT")
@Cacheable

@JsonIgnoreProperties(ignoreUnknown = true)
public class AnswerText {

    @Id  
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "ANSWER_TEXT_ID")  
    private Long answerTextId;

    @ManyToOne
    @JoinColumn(name="answerId", insertable=false, updatable=false, 
                nullable=false)
    private Answer answer;

    @Column(name = "ANSWER_TEXT")  
    private String answerText;

    @Column(name = "LANGUAGE_ID")  
    private Long languageId;

            //getters and setters

当我访问获取结果集时，它显示以下错误

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column 'answertext2_.answerId' in 'field list'

然后我改成下面的

AnswerText.java

@ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "ANSWER_ID", nullable = false) 
    private Answer answer;

答案.java

@OneToMany(fetch = FetchType.EAGER,mappedBy = "answer" )
    @Fetch(FetchMode.JOIN)
    private Set<AnswerText> answerText = new HashSet<AnswerText>();

这不会产生错误，但在调用时会两次获取结果

第二个 HibernateDao 调用是

List<Answer> answerList = questionManager.getAnswersByQuestionId(Long.parseLong("2"));
            System.out.println("answerList :"+answerList1.size());

    @Override
public ArrayList<Answer> getAnswersByQuestionId(Number questionId) {
    Criteria criteria = sessionFactory.getCurrentSession().createCriteria(Answer.class);
    criteria.add(Restrictions.eq("questionId", questionId));
    ArrayList<Answer> answerList = (ArrayList) criteria.list();
    return answerList;
}

请任何人指出我这里出了什么问题。请帮助我。

Answer 1

您已经正确更改了 JoinColumn-name。

我认为您的多个结果必然是:

FetchType.EAGER和选择

FetchMode JOIN As indicated you’ll have to worry about duplicated results. On the other hand JOIN creates the least amount of queries. In a high latency environment a single JOIN could be considerable faster then multiple SELECTS. Keep in mind that joining too much data could put a strain on the database. from http://www.solidsyntax.be/2013/10/17/fetching-collections-hibernate/

使用FetchMode.SELECT，您将得到您想要的结果。