Caso você tenha esses erros:
ERROR: Field 'id' doesn't have a default value
Exception in thread "main" javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: could not execute statement
at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:154)
at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:181)
at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:188)
at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:726)
at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:706)
at testes.TestaRelacionamento.main(TestaRelacionamento.java:29)
Caused by: org.hibernate.exception.GenericJDBCException: could not execute statement
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:47)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:113)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:99)
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:200)
at org.hibernate.dialect.identity.GetGeneratedKeysDelegate.executeAndExtract(GetGeneratedKeysDelegate.java:57)
at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:43)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3200)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3806)
at org.hibernate.action.internal.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:84)
at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:645)
at org.hibernate.engine.spi.ActionQueue.addResolvedEntityInsertAction(ActionQueue.java:282)
at org.hibernate.engine.spi.ActionQueue.addInsertAction(ActionQueue.java:263)
at org.hibernate.engine.spi.ActionQueue.addAction(ActionQueue.java:317)
at org.hibernate.event.internal.AbstractSaveEventListener.addInsertAction(AbstractSaveEventListener.java:330)
at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:287)
at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193)
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:123)
at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:185)
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:128)
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:55)
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:102)
at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:720)
... 2 more
Caused by: java.sql.SQLException: Field 'id' doesn't have a default value
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:965)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3933)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3869)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2524)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2675)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2465)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1915)
at com.mysql.jdbc.PreparedStatement.executeUpdateInternal(PreparedStatement.java:2136)
at com.mysql.jdbc.PreparedStatement.executeUpdateInternal(PreparedStatement.java:2070)
at com.mysql.jdbc.PreparedStatement.executeLargeUpdate(PreparedStatement.java:5187)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2055)
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:197)
... 20 more
Você pode deletar seu database (drop database alura_jpa) e criá-lo novamente (create database alura_jpa).
Eu tive esse erro e isso resolveu meu problema. Espero ter ajudado alguém.
