main.cpp

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// ======================================================================
//  main.cpp
// ======================================================================
//                   This file is a part of the book 
//             "Qt 5.10 Professional programming with C++"
//                       http://qt-book.com
// ======================================================================
//  Copyright (c) 2017 by Max Schlee
// ======================================================================

#include <QtSql>

static bool createConnection()
{
    QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName("addressbook");

    db.setUserName("elton"); 
    db.setHostName("epica"); 
    db.setPassword("password"); 
    if (!db.open()) {
        qDebug() << "Cannot open database:" << db.lastError();
        return false;
    }
    return true;
}

// ----------------------------------------------------------------------
int main(int argc, char** argv)
{
    QCoreApplication app(argc, argv);

    if (!createConnection()) {
        return -1;
    }
    
    //Creating of the data base
    QSqlQuery query;
    QString   str  = "CREATE TABLE addressbook ( "
                         "number INTEGER PRIMARY KEY NOT NULL, "
                         "name   VARCHAR(15), "
                         "phone  VARCHAR(12), "
                         "email  VARCHAR(15) "
                     ");";

    if (!query.exec(str)) {
        qDebug() << "Unable to create a table";
    }

    //Adding some information
    QString strF = 
          "INSERT INTO  addressbook (number, name, phone, email) "
          "VALUES(%1, '%2', '%3', '%4');";

    str = strF.arg("1")
              .arg("Piggy")
              .arg("+49 631322187")
              .arg("piggy@mega.de");
    if (!query.exec(str)) {
        qDebug() << "Unable to make insert opeation";
    }

    str = strF.arg("2")
              .arg("Kermit")
              .arg("+49 631322181")
              .arg("kermit@mega.de");
    if (!query.exec(str)) {
        qDebug() << "Unable to make insert operation";
    }

    if (!query.exec("SELECT * FROM addressbook;")) {
        qDebug() << "Unable to execute query - exiting";
        return 1;
    }

    //Reading of the data
    QSqlRecord rec     = query.record();
    int        nNumber = 0;
    QString    strName;
    QString    strPhone;
    QString    strEmail;

    while (query.next()) {
        nNumber  = query.value(rec.indexOf("number")).toInt();
        strName  = query.value(rec.indexOf("name")).toString();
        strPhone = query.value(rec.indexOf("phone")).toString();
        strEmail = query.value(rec.indexOf("email")).toString();
    
        qDebug() << nNumber << " " << strName << ";\t" 
                 << strPhone << ";\t" << strEmail;
    }

    return 0;
}