Qt数据库查询之事务操作

 if(QSqlDatabase::database().transaction()){
                    bool res1,res2;
                    query.prepare("update booklist set borrowNum=?,restNum=? where bookId=?");
                    query.bindValue(0,++borrownum);
                    query.bindValue(1,--restnum);
                    query.bindValue(2,bookId);
                    res1=query.exec();
                    //qDebug()<<"insert "<<res1;

                    query.prepare("insert into recordlist(bookId,bookName,borrowPeople,borrowTime,backTime,\
                                  backState) values(?,?,?,?,?,?)");
                    query.bindValue(0,bookId);
                    query.bindValue(1,bookName);
                    query.bindValue(2,userName);
                    query.bindValue(3,borrowTime);
                    query.bindValue(4,"");
                    query.bindValue(5,0);
                    res2=query.exec();
                     //qDebug()<<query.lastError();

                    //qDebug()<<"insert "<<res2;
                    if(res1&&res2){
                        if(!QSqlDatabase::database().commit()){
                            QMessageBox::critical(this,"Error","操作失败，将要回滚");
                            if(!QSqlDatabase::database().rollback()){
                                QMessageBox::critical(this,"Error","回滚失败");
                            }
                        }else{
                            doShowBackResult();
                            //qDebug()<<"show ";
                        }
                    }else{
                        qDebug()<<query.lastError();
                        QMessageBox::critical(this,"Error","操作失败，将要回滚");
                        if(!QSqlDatabase::database().rollback()){
                            QMessageBox::critical(this,"Error","回滚失败");
                            qDebug()<<QSqlDatabase::database().lastError();
                        }
                    }

                }