PyQT5. Работа с базой данных

import sys, time
from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
from PyQt5.QtSql import *
from PyQt5.QtCore import *
 
class Example(QWidget):
    def __init__(self):
        super().__init__()
        self.initUI()
 
    def initUI(self):
        db = QSqlDatabase.addDatabase('QPSQL')
        db.setDatabaseName('postgres')
        db.setHostName('localhost')
        db.setUserName('postgres')
        db.setPassword('masterkey')
        db.open()
 
        view = QTableView(self)
        model = QSqlQueryModel(self)
        model.setQuery('SELECT Staffers.surname AS "Surname", '
                        'Staffers.name_ as "Name", '
                        'Staffers.old AS "Old", '
                        'Position_.name_ AS "Position", '
                        'Office.name_ AS "Office", '
                        'Departments_type.name_ AS "Department" '
                        'FROM Staffers, Position_, Office, Departments, Departments_type '
                        'WHERE Staffers.id_position = Position_.key_ '
                        'and Staffers.id_Department = Departments.key_ '
                        'and Departments.id_office = Office.Key_ '
                        'and Departments.id_type_depart = Departments_type.key_;')
        view.setModel(model)
        view.move(10, 10)
        view.resize(617, 315)
 
        #Buttons:
        button1 = QPushButton('Exit', self)
        button1.resize(button1.sizeHint())
        button1.move(50, 400)
        def But1Click():
            if db.close():
                print('close')
            else:
                print('db dont close')
                sys.exit()
        button1.clicked.connect(But1Click)
 
        #Window:
        self.setGeometry(300, 100, 650, 450)
        self.setWindowTitle('Icon')
        self.show()
 
if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())