带有@ManyTomany SQL语法错误的Spring-boot jpa查询

Question

我是一个编程新手，有一个相当复杂的问题。我希望有人知道如何解决以下问题：

@Entity
@Table(name = "contacts")
@JsonInclude(Include.NON_DEFAULT)
public class Contact implements Serializable {
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private double k_Contact; 

@NotNull
private String name;

// There are several other variables here

@ManyToMany
@JoinTable(
        name = "PROJ_CONT",
        joinColumns = @JoinColumn(name = "K_CONTACT", referencedColumnName="K_CONTACT"),
        inverseJoinColumns = @JoinColumn(name = "K_PROJECT", referencedColumnName="K_PROJECT"))
    private Set<Project> projects = new HashSet<>();

@ManyToOne  
@JoinTable(
        name = "CONT$COMPETENCECENTER",
        joinColumns = @JoinColumn(name = "K_CONTACT", referencedColumnName="K_CONTACT"),
        inverseJoinColumns = @JoinColumn(name = "F_COCE_MAIN", referencedColumnName="K_CONT_MEDE_COCE"))
    private Coce coce; 

public Contact() {
}

public Contact(double k_Contact) {
    this.k_Contact = k_Contact;
}

public Contact(double k_Contact, String name, String firstName, String email1, Byte[] picture) {
    this.k_Contact = k_Contact;
    this.name = name;
    this.firstName = firstName;
    this.email1 = email1;
    this.picture = picture;
}

public Contact(double k_Contact, String name, String firstName, String email1, Byte[] picture, Coce coce, Set<Project> projects) {
    this.k_Contact = k_Contact;
    this.name = name;
    this.firstName = firstName;
    this.email1 = email1;
    this.picture = picture;
    this.coce = coce;
    this.projects = projects;
}
// plus getters and setters
}

@Entity
@Table(name = "projects")
@JsonInclude(Include.NON_DEFAULT)
public class Project implements Serializable {
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private double k_Project;

@NotNull
private String name;

@NotNull
private LocalDateTime d_Start;

@NotNull
private LocalDateTime d_End;

public Project() {
}

public Project(double K_PROJECT, String NAME) {
    this.k_Project = K_PROJECT;
    this.name = NAME;
}}

和科斯：

@Entity
@Table(name = "LK_CONT_MEDE_COCE")
@JsonInclude(Include.NON_NULL)
public class Coce implements Serializable {
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private double k_Cont_Mede_Coce;

@NotNull
private String competence_Cente;

@NotNull
private String unipartners;

public Coce() {
}

public Coce(double k_Cont_Mede_Coce, String competence_Cente, String unipartners) {
    this.k_Cont_Mede_Coce = k_Cont_Mede_Coce;
    this.competence_Cente = competence_Cente;
    this.unipartners = unipartners;
}}

我只想要几个变量（这就是为什么我不能做全选）。我还认为我不应该用内部连接来编写广泛的查询，所以我没有这样做（它适用于大多数查询，除了列表变量）。

这是ContactRepository的相关部分：

public interface ContactRepository extends JpaRepository<Contact, Double> {
@Query("select c.k_Contact, c.name, c.firstName, c.email1, c.picture, c.coce, c.project from Contact c where c.k_Contact is :id")
Optional<Contact> findContactById(@Param("id") Double id);
}

MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'as col_6_0_, coce1_.k_Cont_Mede_Coce as k_Cont_M1_3_0_, project3_.k_Project as k' at line 1

如果有什么重要的东西我应该在这里补充，请告诉我。提前道谢！

编辑：应用程序运行时，只有当我尝试在运行时访问特定的数据时才会出现SQL错误。正如所问的，这里是完整的错误，我没有添加它，因为它相当长：

Answer 1

尝试添加到类项目

@ManyToMany(fetch = FetchType.LAZY, mappedBy = "projects")
private Set<Contact> contacts = new HashSet<Contact>();

我的工作示例

@Entity
public class Role {

    @Id
    @Column(name = "id", unique = true, nullable = false)
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @ManyToMany(cascade = CascadeType.ALL)
    @JoinTable(joinColumns = @JoinColumn(name = "role_id"), inverseJoinColumns = @JoinColumn(name = "user_id"))
    private Set<User> users = new HashSet<>();

    [getter / setter]

}


@Entity
public class User {

    @Id
    @Column(name = "id", unique = true, nullable = false)
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy = "users")
    @JsonIgnore
    private Set<Role> userRole = new HashSet<>();

    [getter / setter]

}