我有两张桌子学生和书籍，有很多关系。两者的代码如下。现在，当我尝试运行代码时，我收到错误。
异常[EclipseLink-4002]（Eclipse Persistence Services - 2.3.2.v20111125-r10461）：org.eclipse.persistence.exceptions.DatabaseException 内部异常：com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException：表'acme.book_stud'不存在 错误代码：1146 调用：INSERT INTO book_stud（idStudents，idBooks）VALUES（？，？） bind =＆gt; [2个参数绑定]
似乎JPA正在尝试写入不存在的juction表（在这种情况下，它假定已经创建了一个联结表 books_students ，因此它不会创建一个。）。如果我创建一个books_students但我不想这样做，因为它的JPA责任创建它。有没有一种方法可以明确告诉它创建一个。 ？ （我在这里做了一个疯狂的猜测 - 但我想在创建一个持久单元时我指定“无”我认为这就是为什么它没有创建那个表。我是否正确？无论如何这里是我的学生和书籍类
BOOKS CLASS
@Entity
@Table(name = "books")
@XmlRootElement
@NamedQueries({
@NamedQuery(name = "Books.findAll", query = "SELECT b FROM Books b"),
@NamedQuery(name = "Books.findByIdBooks", query = "SELECT b FROM Books b WHERE b.idBooks = :idBooks"),
@NamedQuery(name = "Books.findByBookName", query = "SELECT b FROM Books b WHERE b.bookName = :bookName"),
@NamedQuery(name = "Books.findByBookType", query = "SELECT b FROM Books b WHERE b.bookType = :bookType")})
public class Books implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 45)
@Column(name = "idBooks")
private String idBooks;
@Size(max = 45)
@Column(name = "BookName")
private String bookName;
@Size(max = 45)
@Column(name = "BookType")
private String bookType;
/******************************************ADDED **********************/
@ManyToMany
@JoinTable(name = "book_stud",
joinColumns = { @JoinColumn(name = "idStudents") },
inverseJoinColumns = { @JoinColumn(name = "idBooks") })
/**************************************ENDED*****************************/
public Books() {
}
public Books(String idBooks) {
this.idBooks = idBooks;
}
public String getIdBooks() {
return idBooks;
}
public void setIdBooks(String idBooks) {
this.idBooks = idBooks;
}
public String getBookName() {
return bookName;
}
public void setBookName(String bookName) {
this.bookName = bookName;
}
public String getBookType() {
return bookType;
}
public void setBookType(String bookType) {
this.bookType = bookType;
}
@Override
public int hashCode() {
int hash = 0;
hash += (idBooks != null ? idBooks.hashCode() : 0);
return hash;
}
@Override
public boolean equals(Object object) {
// TODO: Warning - this method won't work in the case the id fields are not set
if (!(object instanceof Books)) {
return false;
}
Books other = (Books) object;
if ((this.idBooks == null && other.idBooks != null) || (this.idBooks != null && !this.idBooks.equals(other.idBooks))) {
return false;
}
return true;
}
@Override
public String toString() {
return "domain.Books[ idBooks=" + idBooks + " ]";
}
}
学生课程
@Entity
@Table(name = "students")
@XmlRootElement
@NamedQueries({
@NamedQuery(name = "StudentEnroll.findAll", query = "SELECT s FROM StudentEnroll s"),
@NamedQuery(name = "StudentEnroll.findByIdStudents", query = "SELECT s FROM StudentEnroll s WHERE s.idStudents = :idStudents"),
@NamedQuery(name = "StudentEnroll.findByName", query = "SELECT s FROM StudentEnroll s WHERE s.name = :name"),
@NamedQuery(name = "StudentEnroll.findByRoll", query = "SELECT s FROM StudentEnroll s WHERE s.roll = :roll"),
@NamedQuery(name = "StudentEnroll.findBySsn", query = "SELECT s FROM StudentEnroll s WHERE s.ssn = :ssn"),
@NamedQuery(name = "StudentEnroll.findByProgram", query = "SELECT s FROM StudentEnroll s WHERE s.program = :program")})
public class StudentEnroll implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 40)
@Column(name = "idStudents")
private String idStudents;
@Size(max = 45)
@Column(name = "Name")
private String name;
@Column(name = "Roll")
private Integer roll;
@Column(name = "SSN")
private Integer ssn;
@Size(max = 45)
@Column(name = "Program")
private String program;
@JoinColumn(name = "CustomerID", referencedColumnName = "UserID")
@ManyToOne
private Customer customerID;
//@OneToMany(mappedBy = "studentRoll")
@OneToMany(mappedBy = "studentRoll",cascade = CascadeType.REMOVE)//added REMOVE
private Collection<Subject> subjectCollection;
/**************************ADDED*****************************/
@ManyToMany
@JoinTable(name = "book_stud",
joinColumns = { @JoinColumn(name = "idBooks") },
inverseJoinColumns = { @JoinColumn(name = "idStudents") })
/**********************************END**********************/
public StudentEnroll() {
}
public StudentEnroll(String idStudents) {
this.idStudents = idStudents;
}
public String getIdStudents() {
return idStudents;
}
public void setIdStudents(String idStudents) {
this.idStudents = idStudents;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getRoll() {
return roll;
}
public void setRoll(Integer roll) {
this.roll = roll;
}
public Integer getSsn() {
return ssn;
}
public void setSsn(Integer ssn) {
this.ssn = ssn;
}
public String getProgram() {
return program;
}
public void setProgram(String program) {
this.program = program;
}
public Customer getCustomerID() {
return customerID;
}
public void setCustomerID(Customer customerID) {
this.customerID = customerID;
}
@XmlTransient
public Collection<Subject> getSubjectCollection() {
return subjectCollection;
}
public void setSubjectCollection(Collection<Subject> subjectCollection) {
this.subjectCollection = subjectCollection;
}
@Override
public int hashCode() {
int hash = 0;
hash += (idStudents != null ? idStudents.hashCode() : 0);
return hash;
}
@Override
public boolean equals(Object object) {
// TODO: Warning - this method won't work in the case the id fields are not set
if (!(object instanceof StudentEnroll)) {
return false;
}
StudentEnroll other = (StudentEnroll) object;
if ((this.idStudents == null && other.idStudents != null) || (this.idStudents != null && !this.idStudents.equals(other.idStudents))) {
return false;
}
return true;
}
@Override
public String toString() {
return "domain.StudentEnroll[ idStudents=" + idStudents + " ]";
}
}