Add new file

Mainwindow.h

+#ifndef MAINWINDOW_H
+#define MAINWINDOW_H
+
+#include <QMainWindow>
+#include <regist.h>
+#include <userwindow.h>
+#include <QSqlDatabase>
+#include <QSqlQuery>
+#include <QSqlError>
+#include <QDebug>
+
+namespace Ui {
+class MainWindow;
+}
+
+class MainWindow : public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    explicit MainWindow(QWidget *parent = 0);
+    ~MainWindow();
+    void init_database();
+
+signals:
+    void sendinfo(QSqlDatabase,QString);
+    void sendata(QSqlDatabase,QString);
+
+private slots:
+    void on_pushButton_2_clicked();
+
+    void on_pushButton_clicked();
+
+private:
+    Ui::MainWindow *ui;
+    QSqlDatabase db;
+    Regist *registwind;
+    UserWindow *userwind;
+};
+
+#endif // MAINWINDOW_H