问使用Qt在SQLite数据库上执行多线程操作时崩溃

EN

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QtConcurrent/QtConcurrentRun>
#include <database.h>


int main(int argc, char *argv[])
{

QGuiApplication app(argc, argv);
QQmlApplicationEngine engine;
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
Database *db0=new Database();
Database *db1=new Database();
Database *db2=new Database();

QString param0="Select LastUpdateDate From TableLastUpdateLog Where TableName='T1'";
 QString param1="Select LastUpdateDate From TableLastUpdateLog Where TableName='T2'";
  QString param2="Select LastUpdateDate From TableLastUpdateLog Where TableName='T3'";


QtConcurrent::run(db0,&Database::Select,param0);
QtConcurrent::run(db1,&Database::Select,param1);
QtConcurrent::run(db2,&Database::Select,param2);



return app.exec();

void Database::Select(QString query) {

m_db=QSqlDatabase::addDatabase("QSQLITE","myconn");
m_db.setDatabaseName("./mytask.db");
bool result=m_db.open();
if(result==false)
    qDebug()<<"Failed";
else
{
    qDebug()<<"Connection is Success";
    m_qry=new QSqlQuery(m_db);
    m_qry->exec("PRAGMA foreign_keys = ON;");
    m_qry->exec("DSQLITE_THREADSAFE=2");
    m_qry->prepare(query);
    if(m_qry->exec()!=true)
    {
        qDebug()<<"Query Failed:"<<m_qry->lastError();
        qDebug()<<m_qry->lastQuery();
    }
    else
    {
        QSqlRecord rec=m_qry->record();
        while(m_qry->next())
        {
            qDebug()<<m_qry->value("LastUpdateDate").toDateTime();
        }

    }
}

m_db.close();
m_db.removeDatabase("myconn");

//mutex.unlock();   
}