Sql query help



  • I'm trying to work with a simple sqlite db, 1 row, 1 table with two columns, id and name.
    Creating the db works and updating the db works, but reading it does not. I've done
    the query manually at the sqlite3 prompt w/o a problem. query.isValid() is never
    true and query.lastError().text() is empty.

    @
    ////////////////////////////////
    void createTables()
    {
    QSqlQuery query;
    query.exec("create table device(id int primary key, name varchar(20))");
    query.exec("insert into device values(1, '')");

    }

    ////////////////////////////////
    void updateTables()
    {
    QSqlQuery query;
    QString sqlstatement = "UPDATE device SET name='"+daddr+"' WHERE Id=1";
    query.exec(sqlstatement);
    }

    ////////////////////////////////
    void readTables()
    {
    QSqlQuery query;
    query.exec("SELECT name FROM device");

    if (query.isValid())
    daddr = query.value(1).toString();
    else
     daddr = "";
    

    }

    //////////////////////////////////////////////
    MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
    {

     ui->setupUi(this);
    

    QFile Fout("/Applications/myprog/myprog.db");

    if(!Fout.exists())
    {
    dbexists = false;
    }
    else
    {
    dbexists = true;
    }

    dbstring = "/Applications/myprog/myprog.db";

    db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName(dbstring);

    if (!db.open()) {
    QMessageBox::critical(0, qApp->tr("Cannot open database"),
    qApp->tr("Unable to establish a database connection.\n"
    ), QMessageBox::Cancel);

    }

    if (!dbexists)
    createTables();
    else
    readTables();

    ui->device->setText(daddr); 
    

    }

    MainWindow::~MainWindow()
    {
    updateTables();
    db.close();
    delete ui;

    }
    @



  • It's fixed:

    @
    QSqlQuery query;
    query.exec("SELECT name FROM device");
    while (query.next()) {
    daddr = query.value(0).toString();
    }
    @

    I guess the query in the first post was sitting on EOD?


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