问排序QTreeWidget

EN

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QSql>
//more include...
#include <QTreeWidget>

extern QSqlDatabase db;
//more extern...

namespace Ui {
class mainwindow;
class TreeWidgetItem;
}

class TreeWidgetItem : public QTreeWidgetItem
{
    Q_OBJECT

public:
    TreeWidgetItem(QTreeWidget *tree) : QTreeWidgetItem(tree)  {}
    TreeWidgetItem(QTreeWidget * parent, const QStringList & strings)
                   : QTreeWidgetItem (parent,strings)  {}
    bool operator< (const QTreeWidgetItem &other) const
    {
        int column = treeWidget()->sortColumn();
        return text(column).toInt() < other.text(column).toInt();
    }
};

class mainwindow : public QMainWindow
{
    Q_OBJECT

public:
    //...