QT connection MySQL data query failed

problem

Normal at initial query , You can find the data

The software does not operate approximately 10 minute , We can't find the data

You can confirm that the database is still connected

Related codes

        QSqlQuery query;        QString sql = QString("SELECT word,mean,time FROM words WHERE id = '%1'").arg(id);        qDebug() << sql << '\n'; query.exec(sql);        qDebug() << query.size() << '\n'; wordInfo t; while(query.next())        {            qDebug() << "word" << '\n';        }

My solution ideas and tried methods

There is no problem with the time configuration displayed in the database