C++ (Qt)
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QMainWindow>
#include "tablewidgetitem.h"
 
 
namespace Ui {
    class MainWindow;
}
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
 
private slots:
    void on_pushButton_clicked();
 
private:
    Ui::MainWindow *ui;
};
 
#endif // MAINWINDOW_H

C++ (Qt)
#include "mainwindow.h"
#include "ui_mainwindow.h"
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
 
    int countColumn = 1, countRow = 5;
 
 
    ui->tableWidget->setColumnCount( countColumn );
    ui->tableWidget->setRowCount( countRow );
 
    ui->tableWidget->setItem(0,0, new TableWidgetItem("02.2011"));
    ui->tableWidget->setItem(1,0, new TableWidgetItem("10.2009"));
    ui->tableWidget->setItem(2,0, new TableWidgetItem("04.2010"));
    ui->tableWidget->setItem(3,0, new TableWidgetItem("09.2011"));
    ui->tableWidget->setItem(3,0, new TableWidgetItem("09.1990"));
}
 
MainWindow::~MainWindow()
{
    delete ui;
}
 
void MainWindow::on_pushButton_clicked()
{
    ui->tableWidget->setSortingEnabled(true);
    ui->tableWidget->sortItems(0, Qt::DescendingOrder);
}
 

C++ (Qt)
#ifndef TABLEWIDGETITEM_H
#define TABLEWIDGETITEM_H
 
#include <QTableWidgetItem>
#include <QDate>
 
class TableWidgetItem : public QTableWidgetItem
{
public:
    explicit TableWidgetItem(const QString &text, int type = Type);
    bool operator< (const QTableWidgetItem&  other) const;
 
};
 
#endif // TABLEWIDGETITEM_H
 

C++ (Qt)
#include "tablewidgetitem.h"
 
TableWidgetItem::TableWidgetItem(const QString &text, int type) :
    QTableWidgetItem(text,type)
{
}
 
bool TableWidgetItem::operator <(const QTableWidgetItem&  other) const
{
    return(QDate::fromString(other.data( Qt::DisplayRole ).toString(), "MM.yyyy") > QDate::fromString(data(Qt::DisplayRole ).toString(), "MM.yyyy"));
}