Create a windows application with sqlite

[nittalope]

Hi everyone, I'm new on Qt, so maybe my problem is not that big, but I've searched a bit and didn't found a solution yet.
I've written an application using Qt under Linux environment, everything worked well. Then I've compiled it under xp and still everything worked well. Now I want to distribute it on computer that has not Qt installed, so I copied the exe compiled under xp, and with it I copied the dll needed (qtsql4, qtgui4, qtcore4, mingwm10) and when I run the application the "Unable to establish a database connection. This example needs SQLite support. Please read the Qt SQL driver documentation for information how to build it. Click Cancel to exit." message that is in a "connection.h" file that I show below. I really don't know how to go on...

#include <QTimer>
#include <QtSql>
#include <QMessageBox>
 
 static bool createConnection()
 {
    QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
//    db.setDatabaseName(":memory:");
    db.setDatabaseName("yorkshire_db");
     if (!db.open()) {
         QMessageBox::critical(0, qApp->tr("Cannot open database"),
             qApp->tr("Unable to establish a database connection.\n"
                      "This example needs SQLite support. Please read "
                      "the Qt SQL driver documentation for information how "
                      "to build it.\n\n"
                      "Click Cancel to exit."), QMessageBox::Cancel);
         return false;
     }

#include <QTimer>
#include <QtSql>
#include <QMessageBox>

 static bool createConnection()
 {
    QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
//    db.setDatabaseName(":memory:");
    db.setDatabaseName("yorkshire_db");
     if (!db.open()) {
         QMessageBox::critical(0, qApp->tr("Cannot open database"),
             qApp->tr("Unable to establish a database connection.\n"
                      "This example needs SQLite support. Please read "
                      "the Qt SQL driver documentation for information how "
                      "to build it.\n\n"
                      "Click Cancel to exit."), QMessageBox::Cancel);
         return false;
     }

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[mcosta]

to deploy an application that uses plugins you have to follow instructions in http://doc.trolltech.com/4.5/deployment.html.

you must create a "sqldrivers" subdirectory in executable directory and copy the qsqlite drivers into.

[nittalope]

Thank you! I am now reading it... and try to plug things in...

[nittalope]

Ok, I created the /sqldrivers directory and copied sqldrivers inside... but still the same error...
This is my application's directory tree:
\myappdirectory

- myapp.exe
- qtcore4.dll
- qtgui4.dll
- qtsql4.dll
- sqldrivers \

- qsqlite4.dll
- libqsqlite4.a

[mcosta]

you need to have sqlite3.dll in you path. If you don't, you can copy it in sqldrivers folder.

I suggest you to use some tool to discover dependencies. See Dependency Walker

[rexi]

Also, you do not need libqsqlite4.a. This is a static library that would only be required at compile time if you wanted to statically link in Qt's SQLite support. But you do not need to deploy it.

[nittalope]

Thank you everybody...
Well, I did use dependency walker and found out I was missing msjava.dll, fixed the problem, but it wasn't my problem... :P
Still getting the message about sqlite, and dependency didn't show anything about sqlite...

I do copied sqlite3.dll in sqldrivers directory... now I am wondering if there is a version problem with the dlls...
And, by the way, I have to mention that I developed the application in linux, and compiled it in vista, and ported it to a xp enviroment... maybe there is something related to this too?
And maybe I should write a different code to found out the specific problem and not a generic

if (!db.open()) {

if (!db.open()) {

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?!? But in this case... I don't know what to write...

[nish]

use QSqlDatabase::lastError ()and QSqlError::text ()

[nittalope]

Well... before to start to track the error I just wanted to check if installing qt on the xp machine the app would work and... surprise! No.
So I installed the windows version of QT SDK and compiled the source files and... f**k! Same problem! Seems that sqlite drivers are not installed either...
Now I'm recompiling qt... but the question is: even without qt installed I need the application to work!

[nittalope]

Just to say that everything now works correct. Just needed to delete all the non .h, .cpp, .pro file (clean up the directory...) and then compile.

I compile in XP environment.

On the deployment machine I had the directory with my exe, with mingwm10.dll (taken from mingw directory in qt installation directory) and qtcore4, qtsql4, qtgui4 dlls (taken from bin directory in qt installation directory), than a directory "sqldrivers" and there the qsqlite4.dll taken from qt/plugins/sqldrivers directory in the qt installation directory.

Everytime I change something in my application I simply compile in the XP environment and then copy the exe file in the main directory.

Happy, at the end.