原因：java。sql。SQLException:找不到列“id”

Question

我想获取一些字段，然后将其设置为我的测试。实体我的SQL查询：

                query = "SELECT t.id as tId, t.test_name, t.duration, q.id as qId, " +
                    "q.question as question, q.is_multichoice as is_multichoice, " +
                    "q.is_open as is_open, a.id as aId, a.answer_text as answer_text  FROM result r " +
                    "JOIN test t ON r.test_id = t.id " +
                    "JOIN user u ON r.user_id = u.id " +
                    "JOIN question q ON t.id = q.test_id JOIN answer a ON q.id = a.question_id " +
                    "WHERE t.id = :testId AND u.id = :userId AND r.permission = :permissionId " +
                    "AND q.archived = false AND a.archived = false", resultClass = com.bionic.entities.Test.class)

测试实体：

public class Test {
@Id
@Column(name = "id")
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@Column(name = "duration", nullable = false)
private int duration;
@Column(name = "test_name", nullable = false, unique = true)
private String testName;
@Column(name = "archived", nullable = false)
private boolean archived;
@OneToMany(mappedBy = "test", fetch = FetchType.EAGER)
private Set<Question> questions;
@ManyToMany(mappedBy = "tests")
private Set<User> users;

问题实体：

public class Question {
@Id
@Column(name = "id")
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@Column(name = "is_multichoice", nullable = false)
private boolean isMultichoice;
@Column(name = "is_open", nullable = false)
private boolean isOpen;
@Column(name = "picture")
private String picture;
@Column(name = "question")
private String question;
@ManyToOne
@JoinColumn(name = "test_id", nullable = false)
private Test test;
@Column(name = "archived", nullable = false)
private boolean isArchived;
@OneToMany(mappedBy = "question", fetch = FetchType.EAGER)
private Set<Answer> answers;

答复实体：

public class Answer {
@Id
@Column(name = "id")
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@Column(name = "answer_text", nullable = false)
private String answerText;
@Column(name = "mark", nullable = false)
private int mark;
@ManyToOne
@JoinColumn(name = "question_id")
private Question question;
@Column(name = "picture")
private String picture;
@Column(name = "archived", nullable = false)
private boolean isArchived;

但是，在执行此查询后，我得到了以下验证：

Caused by: java.sql.SQLException: Column 'id' not found.

道。类别：

    public Test getCurrentTest(long id, long testId, long permissionId) {
    Query query = em.createNamedQuery("getCurrentTestById");
    query.setParameter("userId", id);
    query.setParameter("testId", testId);
    query.setParameter("permissionId", permissionId);
    return (Test) query.getSingleResult();
}

我做错了什么

Answer 1

查询不会返回名为id的字段。它的字段名为aId, qId, and tId

您需要在实体中使用正确的列名。例如，在测试实体中，您声明了一个名为id的列。除了查询不返回名为id的列外，它还返回一个名为tId的列。下面是需要更改的示例

public class Test {
@tId
@Column(name = "tId")
@GeneratedValue(strategy = GenerationType.AUTO)
private long tId;
 ....