My second connection in sqlite is not work.

[MhM93]

I think daba2 can not connect with another database.yes when i click my button to call connect method to second database, my app is crashed(my app run on embedded device) and my program is closed. (also try catch is not work to find the error text)

[Fuel]

@MhM93 said in My second connection in sqlite is not work.:

daba2 = QSqlDatabase::addDatabase("QSQLITE","BkupDB");//not dbConnection
daba.setDatabaseName(dabkup);

I see here that you use the wrong Variable. you need to use daba2.setDatabaseName(dabkup)

[MhM93]

in this code:

daba2.setDatabaseName(dabkup)

dabkup is my input method parameter and it is my backup database path and name

[artwaw]

@MhM93 But @Fuel is right - the code you posted has an error: you add second database but just afterwards change database name on the first one, not setting name on the second. And then you try to open it.

[MhM93]

thanks for both reply(@Fuel and @artwaw )
Sorry but I think I need more describe. could you please about it or write a little example code for me?
When I search I see these codes:
[https://forum.qt.io/topic/76810/use-two-or-more-sqlite-database-at-the-same-time/3]

db= QSqlDatabase::addDatabase("QSQLITE", "first_connection");
fallas= QSqlDatabase::addDatabase("QSQLITE", "second_connection");

after define connection I set the database name with the database name and path.
please write an example for me. sorry

[mrjj]

@MhM93 said in My second connection in sqlite is not work.:

hi
As @artwaw says

 bool DB::MergeData(QString dabkup)
 {
     try{
     daba2 = QSqlDatabase::addDatabase("QSQLITE","BkupDB");
     daba.setDatabaseName(dabkup); <<<<<<<<<<<< should be daba2

[MhM93]

thanks for answer and excuse me for silly mistake, I change it but again my app crash at this line
(I use qt4.8.6)

bool DB::MergeData(QString dabkup)
{

        qDebug("db backup start");
try{
        daba2 = QSqlDatabase::addDatabase("QSQLITE","BkupDB");   // = in this line
        }catch(...){
        qDebug()<<daba2.lastError().text();
    }
        qDebug("1");
        daba2.setDatabaseName(dabkup);
        qDebug("2");

        if(!daba2.open())
        {
            qDebug("db backup can not open");
            return false;
        }

[mrjj]

That is odd if it crashed there.
Do you allocate DB before you call MergeData ?
Please Show calling code.

[MhM93]

class PenDrive : public QWidget
{
    Q_OBJECT

public:
    explicit PenDrive(QWidget *parent = 0,SerialPort *finger=0);
    ~PenDrive();
    DB *database;

and:

void PenDrive::on_btnUploadUser_clicked()
{
    md=new MessageDialog(this);
    if(!CheckUSB())
    {
        md->error( tr("FAIL"), tr("Sorry.The USB is not detected at udisk0."));
        return;
    }
    QFile::copy("/media/usb/IODBbkup", "IODBbkup");
    qDebug("before call database");
    if(database->MergeData("IODBbkup")){
        md->success(tr("Step one"),tr("Successfully finished step one, \n Please wait to write data on sensor."));
        fdb->WriteFinger(NULL);
    }
    else
        md->error(tr("Step one"),tr("Error occured in step one."));

}

and merg code:

bool DB::MergeData(QString dabkup)
{
    try{
        qDebug("db backup start");
        
        daba2 = QSqlDatabase::addDatabase("QSQLITE","BkupDB");//not dbConnection
        qDebug("1");
        daba2.setDatabaseName(dabkup);
        qDebug("2");
    
        if(!daba2.open())
        {
            qDebug("db backup can not open");
            return false;
        }
    
        qDebug("db backup is open");
        //-----------------------------------------------------------
        QSqlQuery q("select * from userinfo;",QSqlDatabase::database("BkupDB"));
        QSqlQueryModel *lst=new QSqlQueryModel();
        lst->setQuery(q);
        int pid=0;
        int id=0;
        bool admin=false,active=false;
    
        //insert userinfo at first step
        for(int i = 0; i < lst->rowCount(); ++i)
        {
            pid=lst->record(i).value(1).toInt();
            admin=lst->record(i).value(2).toInt();
            active=lst->record(i).value(3).toInt();
            q.prepare("select count(UI_PID) from userinfo where UI_PID=:pid;");
            q.bindValue(0,pid);
            //insert into userinfo main database
            //from backup database
            qDebug()<<"pid:"<<pid<<"  admin:"<<admin<<"  active:"<<active<<"  ";
            if(q.exec())
                while(q.next())
                {
                    if(q.value(0).toInt()==0)
                    {
                        id=GetMaxUserID(1).toInt();
                        IE_userinfo(id,pid,admin,active);
                    }
                }
        }
        MergeAuthenticate();
        daba2.close();
    }catch(...){
        qDebug()<<daba2.lastError().text();
    }
    qDebug()<<daba2.lastError().text();

return false;
}

output is :

before call database
db backup start

[mrjj]

@MhM93 said in My second connection in sqlite is not work.:

DB *database;

Do you new this ?
DB *database = new DB;

Else you crash if u call functions on it.

[MhM93]

@mrjj said in My second connection in sqlite is not work.:

That is odd if it crashed there.
Do you allocate DB before you call MergeData ?
Please Show calling code.

really thanks, again silly mistake. I add new and it is true. but in whole of my app does not use new and all of them worked.
could you explain it to me?(So sorry)

[mrjj]

@MhM93

Hi
If you declare something as pointer ( with *) you need to call new
to have it be an actual object. else it just points to random location in memory.

So
DB My1; // fine. its actual object, not pointer

DB *My1; // just pointer. Points to nothing valid yet

My1= new DB; // now it points to a real object

[MhM93]

thank you :)