class ExampleApp(QtWidgets.QMainWindow, design.Ui_MainWindow):
def __init__(self):

    super().__init__()
    self.setupUi(self)
    self.connect_mysql.clicked.connect(self.on_click)
    self.dialog = MainMenu()
def on_click(self):
    try:
        ip = self.ip.text()
        user = self.user.text()
        password = self.password.text()
        port = self.port.text()
        db = self.db.text()
        mydb = mysql.connector.connect(
          host=ip,
          user=user,
          passwd=password,
          database=db
            )
        mycursor = mydb.cursor()
        self.close()
        self.dialog.show()

    except:
        QMessageBox.about(self, "Message", "Something went wrong...")