Qt下sqlite正常工作一段时间后创建不了表单插入不了数据，求大神指点

char channel[]="ABCDEFGHIJKLMNOP";
unsigned int dao;
QString dbcopy;
bool dbflag=0;
int dings=0;
char f0=0;
char f5=0;

QTimer *readTimer = new QTimer();
QTimer *readTimers = new QTimer();

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    readTimers->start(20000);
    connect(readTimers,SIGNAL(timeout()),this,SLOT(todo()));
    connect(readTimer,SIGNAL(timeout()),this,SLOT(readMyCom()));
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::readMyCom()
{
    readTimer->stop();
    bool readw_flag = 0;
    if(!readw_flag)
    {
           QDateTime time = QDateTime::currentDateTime();//获取系统现在的时间
           QString timestr = time.toString("yyyyMMddhhmm"); //设置显示格式
           QString datedir=QString("%1").arg(timestr.left(6));//  文件夹
           QString dbname;
           if((dao<16)&&(dbflag==0))
          {
           dbname=QString("./%1/%2.db").arg(timestr.left(6)).arg(timestr.mid(4,8));
           dbcopy=QString(dbname);
           dbflag=1;
           qDebug()<<"name copy"<          }
           else
            dbname=QString(dbcopy);

            QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE","mySQLite");
            db.setDatabaseName(dbname);
            if(!db.open())
                qDebug()<<"cann`t open db."<            QSqlQuery query=QSqlQuery::QSqlQuery(db);

            bool    bsuccess = false;

            QString create=QString("create table %1(id integer primary key autoincrement,count integer);").arg(channel[dao]);
             if(query.exec(create) == false)
               {
                   qDebug() << "cann`t creat db table" << endl;  
               }

             QTime    tmpTime;
             if(!db.transaction())qDebug()<<"transaction begin error!";
             tmpTime.start();

            QString dat;
            qDebug()<<"write  table : "<
            for(unsigned int p=0;p<1024;p++)
            {            
               dat= QString("insert into %1(id,count) values(\'%2\',\'%3\');").arg(channel[dao]).arg(p).arg(p);
               bsuccess=query.exec(dat);
                if (!bsuccess)
                 {
                qDebug()<<"query insert table channel error!"<                break;
                 }
            }            

            if(!db.commit())        //提交事务
            {
                if(db.rollback())
                 qDebug()<<"rollback";
                else qDebug()<<"rollback error!";
            }
            qDebug()<<"records take :"<             db.close(); //

              readw_flag = 1;
}

    if(readw_flag==1)
    {
        QSqlDatabase::removeDatabase("mySQLite");  
    }

    if(readw_flag)
    {
        readw_flag=0;
        dao++;
        if(dao<16)
        {
            qDebug()<<"write  :"<            readTimer->start(1000);
        }
        else
        {
            dbflag=0;
            readTimers->start(20000);
        }
    }               
}

void MainWindow::todo()
{
    QDateTime time = QDateTime::currentDateTime();//获取系统现在的时间
    QString tstr = time.toString("yyyyMMddhhmm"); //设置显示格式
    QString date5=QString("%1").arg(tstr.right(1));
    int shi=date5.toInt();
    qDebug()<<"time now :"<    if((shi==5)&&(f5==0))
    {
        dings=1;f5=1;f0=0;
    }
    if((shi==0)&&(f0==0))
    {
        dings=1;f0=1;f5=0;
    }

    if(dings>=1)
    {
     dings=0;
     readTimers->stop();
     readTimer->start(1000);    

     dao=0;
     dbflag=0;

    dbcopy=" ";
    qDebug()<<" write  :"<    }
    else
    {
        qDebug()<<" time%5 =0  ?? "<    }
}