- Qt 5.5
- Qt SQL
- Books
- initdb.h Example File
- Qt 5.5.1 Reference Documentation

# initdb.h Example File

books/initdb.h

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the demonstration applications of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:LGPL21$
    ** Commercial License Usage
    ** Licensees holding valid commercial Qt licenses may use this file in
    ** accordance with the commercial license agreement provided with the
    ** Software or, alternatively, in accordance with the terms contained in
    ** a written agreement between you and The Qt Company. For licensing terms
    ** and conditions see http://www.qt.io/terms-conditions. For further
    ** information use the contact form at http://www.qt.io/contact-us.
    **
    ** GNU Lesser General Public License Usage
    ** Alternatively, this file may be used under the terms of the GNU Lesser
    ** General Public License version 2.1 or version 3 as published by the Free
    ** Software Foundation and appearing in the file LICENSE.LGPLv21 and
    ** LICENSE.LGPLv3 included in the packaging of this file. Please review the
    ** following information to ensure the GNU Lesser General Public License
    ** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
    ** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
    **
    ** As a special exception, The Qt Company gives you certain additional
    ** rights. These rights are described in The Qt Company LGPL Exception
    ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
    **
    ** $QT_END_LICENSE$
    **
    ****************************************************************************/

    #ifndef INITDB_H
    #define INITDB_H

    #include <QtSql>

    void addBook(QSqlQuery &q, const QString &title, int year, const QVariant &authorId,
                 const QVariant &genreId, int rating)
    {
        q.addBindValue(title);
        q.addBindValue(year);
        q.addBindValue(authorId);
        q.addBindValue(genreId);
        q.addBindValue(rating);
        q.exec();
    }

    QVariant addGenre(QSqlQuery &q, const QString &name)
    {
        q.addBindValue(name);
        q.exec();
        return q.lastInsertId();
    }

    QVariant addAuthor(QSqlQuery &q, const QString &name, const QDate &birthdate)
    {
        q.addBindValue(name);
        q.addBindValue(birthdate);
        q.exec();
        return q.lastInsertId();
    }

    QSqlError initDb()
    {
        QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
        db.setDatabaseName(":memory:");

        if (!db.open())
            return db.lastError();

        QStringList tables = db.tables();
        if (tables.contains("books", Qt::CaseInsensitive)
            && tables.contains("authors", Qt::CaseInsensitive))
            return QSqlError();

        QSqlQuery q;
        if (!q.exec(QLatin1String("create table books(id integer primary key, title varchar, author integer, genre integer, year integer, rating integer)")))
            return q.lastError();
        if (!q.exec(QLatin1String("create table authors(id integer primary key, name varchar, birthdate date)")))
            return q.lastError();
        if (!q.exec(QLatin1String("create table genres(id integer primary key, name varchar)")))
            return q.lastError();

        if (!q.prepare(QLatin1String("insert into authors(name, birthdate) values(?, ?)")))
            return q.lastError();
        QVariant asimovId = addAuthor(q, QLatin1String("Isaac Asimov"), QDate(1920, 2, 1));
        QVariant greeneId = addAuthor(q, QLatin1String("Graham Greene"), QDate(1904, 10, 2));
        QVariant pratchettId = addAuthor(q, QLatin1String("Terry Pratchett"), QDate(1948, 4, 28));

        if (!q.prepare(QLatin1String("insert into genres(name) values(?)")))
            return q.lastError();
        QVariant sfiction = addGenre(q, QLatin1String("Science Fiction"));
        QVariant fiction = addGenre(q, QLatin1String("Fiction"));
        QVariant fantasy = addGenre(q, QLatin1String("Fantasy"));

        if (!q.prepare(QLatin1String("insert into books(title, year, author, genre, rating) values(?, ?, ?, ?, ?)")))
            return q.lastError();
        addBook(q, QLatin1String("Foundation"), 1951, asimovId, sfiction, 3);
        addBook(q, QLatin1String("Foundation and Empire"), 1952, asimovId, sfiction, 4);
        addBook(q, QLatin1String("Second Foundation"), 1953, asimovId, sfiction, 3);
        addBook(q, QLatin1String("Foundation's Edge"), 1982, asimovId, sfiction, 3);
        addBook(q, QLatin1String("Foundation and Earth"), 1986, asimovId, sfiction, 4);
        addBook(q, QLatin1String("Prelude to Foundation"), 1988, asimovId, sfiction, 3);
        addBook(q, QLatin1String("Forward the Foundation"), 1993, asimovId, sfiction, 3);
        addBook(q, QLatin1String("The Power and the Glory"), 1940, greeneId, fiction, 4);
        addBook(q, QLatin1String("The Third Man"), 1950, greeneId, fiction, 5);
        addBook(q, QLatin1String("Our Man in Havana"), 1958, greeneId, fiction, 4);
        addBook(q, QLatin1String("Guards! Guards!"), 1989, pratchettId, fantasy, 3);
        addBook(q, QLatin1String("Night Watch"), 2002, pratchettId, fantasy, 3);
        addBook(q, QLatin1String("Going Postal"), 2004, pratchettId, fantasy, 3);

        return QSqlError();
    }

    #endif