Extract Data from excel using QODBC return empty string

[AmrCoder]

I use this code from qt wiki examples here
this my code in the button press slot

void MainWindow::on_pushButton_clicked()
{
  QSqlDatabase db = QSqlDatabase::addDatabase("QODBC");
  db.setDatabaseName("DRIVER={Microsoft Excel Driver (*.xls, *.xlsx, *.xlsm, *.xlsb)};DBQ=" + QString("D:\\Book1.xlsx"));
  if(db.open())
  {
  qDebug() << "Open"; // printed and it's open no problem
  QSqlQuery query("select '' from [" + QString("Sheet1") + "$]"); // Select range, place A1:B5 after $
  while (query.next()) // excuted
  {
  QString column1= query.value(0).toString();
  qDebug() << "value = " << column1; // get empty string ""
  }
  qDebug() << "Error = " << query.lastError().text(); // output empty string no error in the query !!
  }
  else {
  qDebug() << db.lastError().text();
  }
}

what is return is

Open
value = ""
value = ""
value = ""
value = ""
Error = " "

the excel file contains data iam sure 4 * 3 in the excel file so what is wrong or make the example not work for me
from the db error there is no error output so what cause this problem
second i try this LibXL library here it's works great and the best library to use for excel but it's not free
i ask if there is same library for free for read and write like this and support the xlsx excel file
Thanks in advance

[VRonin]

Not really sure why that blog suggests select ''' see https://www.simple-talk.com/sql/database-administration/getting-data-between-excel-and-sql-server-using-odbc/ use select * from [Sheet1$] (and make sure the sheet is actually called Sheet1)

i ask if there is same library for free for read and write like this and support the xlsx excel file

It's not perfect but does the basics: https://github.com/VSRonin/QtXlsxWriter

If you have excel installed you can use QAxObject to handle it instead

[AmrCoder]

Thank you for your reply @VRonin it solved by using select * from [Sheet1$] query
but i have a problem with the project on github you give me when i try to use it in my project i add this
to my .pro file

include($$PWD/src/xlsx/qtxlsx.pri)

i take the src folder and add it to my project folder and i use this code as a test to extract data from .xlsx file

void MainWindow::on_pushButton_clicked()
{
    using namespace QXlsx;
    QXlsx::Document xlsx("D:/Book1.xlsx");
    int row = xlsx.dimension().rowCount();
    int col = xlsx.dimension().columnCount();
    qDebug() << "row = " << row << " " << " col = " << col;
    for (int i = 0; i < row; i++) {
        for (int j = 0; j < col; j++) {
            std::cout << xlsx.read(i,j).toString().toStdString() << " ";
        }
        std::cout << std::endl;
    }
    fflush(stdout);
}

when i start to build i get alot of

-1: error: undefined reference to `__imp__ZN12QApplicationC1ERiPPci'

about 390 error so what i do wrong in the link part ?
i try to use this project but i got another problem it was an error in QzipReader.cpp file as i rember but on another user on github but i can't solve it
iam using
Qt 5.7 Mingw
Os : windows 10

[VRonin]

you are using Usage 2 I imagine. could you try this basic project (link expires in 2 days) and see if you can compile it?

P.S.
I'm not a lawyer but since this approach breaks binary compatibility it might invalidate the LGPL license leaving you with either the GPL or commercial options only

[AmrCoder]

it built fine both the new you sent to me and the one on github with MSVC 2015 and the application start and the data extracted!
is there a problem with the mingw compiler with qt 5.7?
when I build it with 5.6.2 it built but when I start the application crash!
i don't know why too

[AmrCoder]

sorry it was a problem with my qt compiler i built it again and it compiled Thank you @VRonin