I cant connect my Qt to Sqlite

wenks21

Hi there! I'm new in Qt and I want to learn more about it..

When I try to connect my database in Sqlite to Qt I Encounter these errors. Please help me to fix my codes..
thanks in advance..^_^

here is my code:
@#include "mainwindow.h"
#include <QtSql/QSqlDatabase>
#include <QtDebug>
#include <QtGui/QApplication>

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

//MainWindow mainWindow;
//mainWindow.setOrientation(MainWindow::ScreenOrientationAuto);
//mainWindow.showExpanded();

QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
db.setDatabaseName("C:\sqlite3\sample.db");

if(!db.open())
{
    qDebug(); << db.lastError();
    qFatal("Failed to connect!");
}

else

qDebug("Connected.");



return app.exec();

}
@

I got these error:
error: expected primary-expression before '<<' token
error: invalid use of incomplete type 'struct QSqlError'
error: forward declaration of 'struct QSqlError'

secretNinja

You have written on line 19: @qDebug(); << ...@ There shouldn't be ; there.

leon.anavi

[quote author="secretNinja" date="1304147863"]You have written on line 19: @qDebug(); << ...@ There shouldn't be ; there.[/quote]

Yes, that ; must be causing the error.

Btw there are really nice articles about SQLite in "Forum Nokia.":http://wiki.forum.nokia.com/index.php/CS001504_-_Creating_an_SQLite_database_in_Qt

Regards,
Leon

wenks21

so what should be there? :) thanks..

wenks21

ok thanks..I'll try the link..:)

secretNinja

Only remove ; .

leon.anavi

[quote author="wenks21" date="1304148870"]so what should be there? :) thanks..[/quote]

Just follow secretNinja's advice and remove ; because the << operator is overloaded for "qDebug":http://doc.qt.nokia.com/latest/qdebug.html

You may also need to call text() because qDebug does not expect QSqlError:
@
qDebug() << db.lastError().text();
@

wenks21

when i remove that line of codes. I got these errors:
error: QSqlDatabase: No such file or directory,
error: 'QSqlError' does not name a type,
error: 'QSqlDatabase' does not name a type,

I'm very sorry for being newbie.. :)

leon.anavi

[quote author="wenks21" date="1304150060"]when i remove that line of codes. I got these errors:
error: QSqlDatabase: No such file or directory,
error: 'QSqlError' does not name a type,
error: 'QSqlDatabase' does not name a type,

I'm very sorry for being newbie.. :)

[/quote]

Make sure you have included all required headers and include the "QtSql Module ":http://doc.qt.nokia.com/latest/qtsql.html at your pro file:

@QT += sql@

If you are a newbie it is better to stick to some examples and tutorials :)

Regards,
Leon

wenks21

wow thank you very much! Now it's working.. :)

wenks21

I still have a question. Why is that when I re-run the program the console says that 'Cannot retrieve debugging output!'

leon.anavi

[quote author="wenks21" date="1304151460"]I still have a question. Why is that when I re-run the program the console says that 'Cannot retrieve debugging output!' [/quote]

Please check this thread from Qt Center: "Cannot retrieve debugging output!":http://www.qtcentre.org/threads/37438-Cannot-retrieve-debugging-output!

Please do not use a single thread for multiple question from different issues because after that it will be difficult to track down the main issue.

Best regards,
Leon

wenks21

ok i'm sorry.. thanks again it helps a lot..:)

owenzhao

This helps me a lot. :)
[quote author="leon.anavi" date="1304149339"][quote author="wenks21" date="1304148870"]so what should be there? :) thanks..[/quote]

Just follow secretNinja's advice and remove ; because the << operator is overloaded for "qDebug":http://doc.qt.nokia.com/latest/qdebug.html

You may also need to call text() because qDebug does not expect QSqlError:
@
qDebug() << db.lastError().text();
@

[/quote]

francomartins

it's solved wenks21 ?