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Connecting to the existent database

Before setting the connection with database we should first load the QIBASE plug-in. If you decide to use the plug-in and load it manually, then the following code is for you (with assumption that plug-in is in the same folder with EXE file).

Code: Alles auswählen

 …
    if(!pluginLoader_.isLoaded())
    {
        pluginLoader_.setFileName(QApplication::instance()->applicationDirPath() +
 QDir::separator() + qtIBasePluginName_);
        
        if (!pluginLoader_.load())
        {            
            //// Loading SQL Driver failed.;
            isInitialized_ = false;
            return false;
        }
    }

    QObject* object = pluginLoader_.instance();

    if (object == NULL)
    {            
        //Loading SQL Driver Instance failed.;

        pluginLoader_.unload();
        return false;
    }

    QSqlDriverPlugin* plugin = qobject_cast<QSqlDriverPlugin*>(object);

    if (plugin == NULL)
    {            
        //QSqlDriverPlugin == NULL;
        pluginLoader_.unload();
        return false;
    }

    driver_ = plugin->create("QIBASE");

    if (driver_ == NULL)
    {            
        //Loading QIBASE Driver Instance failed.;
        pluginLoader_.unload();
        return false;
    }

    isInitialized_ = true;

    return isInitialized_;
…

Now when the plug-in for working with FireBird is loaded, we can start with the setting the connection to our database.

QSqlDatabase::addDatabase("QIBASE");

#include <QtSql>
#include <QMessageBox>
#include "mainwindow.hpp"

QSqlError MainWindow::initDb()
{
    db = QSqlDatabase::addDatabase("SQLITE");
    db.setDatabaseName(QDir::currentPath() + "/test.db");
    if (!QFile(db.databaseName()).exists())
    {
        QMessageBox MessageBox;
        MessageBox.setIcon(QMessageBox::Information);
        MessageBox.setWindowTitle(tr("Database not found!"));
        MessageBox.setText(tr("Database not found.\nA new Database will be created."));
        MessageBox.setStandardButtons(QMessageBox::Ok);
        MessageBox.exec();
    }

    if (!db.open())       //<-- Hier bricht er ab
        return db.lastError();

    return QSqlError();
}