Необходимо сделать выборку данных из связанных таблиц типа отношения «многие ко многим».Как вы можете сделать выбор данных из таблиц в отношениях многие ко многим, используя jpa?Выдает ОШИБКУ error: Table 'tets.usergroup' does not exist.
Я искал ответ в Google, но Google не помог.Я пытался прописать суть по-другому, это тоже не помогло.
@Entity
@Table(name = "USERS")
public class User {
private long id;
private String username;
private String password;
private String email;
private Set<UserGroup> userGroups = new HashSet<UserGroup>();
public User() {
}
public User(String username, String password, String email) {
this.username = username;
this.password = password;
this.email = email;
}
public void addGroup(UserGroup group) {
this.userGroups.add(group);
}
@Id
@GeneratedValue
@Column(name = "USER_ID")
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
@OneToMany(mappedBy = "user")
public Set<UserGroup> getUserGroups() {
return userGroups;
}
public void setUserGroups(Set<UserGroup> groups) {
this.userGroups = groups;
}
public void addUserGroup(UserGroup userGroup) {
this.userGroups.add(userGroup);
}
}
Класс группы пользователей
@Entity
@Table(name = "USERS_GROUPS")
public class UserGroup {
private long id;
private User user;
private Group group;
// additional fields
private boolean activated;
private Date registeredDate;
@Id
@GeneratedValue
@Column(name = "USER_GROUP_ID")
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "USER_ID")
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "GROUP_ID")
public Group getGroup() {
return group;
}
public void setGroup(Group group) {
this.group = group;
}
public boolean isActivated() {
return activated;
}
public void setActivated(boolean activated) {
this.activated = activated;
}
@Column(name = "REGISTERED_DATE")
@Temporal(TemporalType.DATE)
public Date getRegisteredDate() {
return registeredDate;
}
public void setRegisteredDate(Date registeredDate) {
this.registeredDate = registeredDate;
}
}`@Entity
@Table(name = "GROUPS")
public class Group {
private long id;
private String name;
private Set<UserGroup> userGroups = new HashSet<UserGroup>();
public Group() {
}
public Group(String name) {
this.name = name;
}
@Id
@GeneratedValue
@Column(name = "GROUP_ID")
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@OneToMany(mappedBy = "group")
public Set<UserGroup> getUserGroups() {
return userGroups;
}
public void setUserGroups(Set<UserGroup> groups) {
this.userGroups = groups;
}
public void addUserGroup(UserGroup userGroup) {
this.userGroups.add(userGroup);
}
}`
И какое-то исключение
ERROR: Table 'tets.usergroup' doesn't exist
Exception in thread "main" org.hibernate.exception.SQLGrammarException: could not extract ResultSet
at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:82)
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:125)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:110)
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:61)
at org.hibernate.loader.Loader.getResultSet(Loader.java:2040)
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1837)
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1816)
at org.hibernate.loader.Loader.doQuery(Loader.java:900)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:342)
at org.hibernate.loader.Loader.doList(Loader.java:2526)
at org.hibernate.loader.Loader.doList(Loader.java:2512)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2342)
at org.hibernate.loader.Loader.list(Loader.java:2337)
at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:338)
at org.hibernate.internal.SessionImpl.listCustomQuery(SessionImpl.java:1833)
at org.hibernate.internal.AbstractSessionImpl.list(AbstractSessionImpl.java:231)
at org.hibernate.internal.SQLQueryImpl.list(SQLQueryImpl.java:157)
at net.codejava.hibernate.Many2ManyTester.select_filter(Many2ManyTester.java:184)
at net.codejava.hibernate.Many2ManyTester.main(Many2ManyTester.java:216)
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 'tets.usergroup' doesn't exist
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.Util.getInstance(Util.java:386)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1054)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4190)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4122)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2570)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2731)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2818)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2157)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2324)
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:56)
... 15 more