def onAddUser(self):
        data = Database()

        user = User()
        user.name = self.editName.text()
        user.username = self.editUsername.text()
        user.passWord = self.editPass.text()

        try:
            data.insertUser(user)
        except sqlite3.IntegrityError:
            msg = QtWidgets.QMessageBox()
            msg.setIcon(QtWidgets.QMessageBox.Warning)
            msg.setText("Your username has already existed !!!")
            msg.setInformativeText("Please choose another username !!!")
            msg.setStandardButtons(QtWidgets.QMessageBox.Ok)
            msg.exec()
            return

        self.addUserIntoTable(user)
        data.closeDatabase()

        self.editName.clear()
        self.editPass.clear()
        self.editUsername.clear()
    def onCellClick(self, row, col):
        user = User()
        user.name = self.tableUser.item(row, 0).text()
        user.username = self.tableUser.item(row, 1).text()
        user.passWord = self.tableUser.item(row, 2).text()

        self.editName.setText(user.name)
        self.editUsername.setText(user.username)
        self.editPass.setText(user.passWord)