二级窗口关闭时刷新主窗口 PyQt5

在PyQt5中，我有一个窗口，它从数据库中读取信息并将这些信息添加到一个widget中。还有一个窗口，当它打开时，向数据库添加一个新的表。我想做的是在第二个窗口关闭时重新加载主窗口。我不想把二级窗口改为 QDialoge ，需要使用 .show() ，而不是 .exec_() 。我有什么办法可以做到这一点吗。

There is my code:

import sys
import sqlite3
from PyQt5.QtWidgets import QApplication, QLabel, QMainWindow, QPushButton, QListWidget, QVBoxLayout, QWidget
from PyQt5.QtCore import Qt
class SecondWindow(QMainWindow):
    def __init__(self, *args, **kwargs):
        super(SecondWindow, self).__init__(*args, **kwargs)
        self.setWindowTitle("App 2")
        label = QLabel("INSERTED VALUES")
        label.setAlignment(Qt.AlignCenter)
        self.setCentralWidget(label)
        #Open Database
        self.conn = sqlite3.connect("connections.db")
        self.cursor = self.conn.cursor()
        #Add New Table To Database
        self.cursor.execute('''CREATE TABLE `New`
                     (name text, GD text)''')
        self.conn.commit()
        self.conn.close()
class MainWindow(QMainWindow):
    def __init__(self, *args, **kwargs):
        super(MainWindow, self).__init__(*args, **kwargs)
        self.setWindowTitle("App")
        self.list = QListWidget()
        self.cursorCount = 0
        #Open Database
        self.conn = sqlite3.connect("connections.db")
        self.cursor = self.conn.cursor()
            #Try To Create A Table If It Doesn't exit
            self.cursor.execute('''CREATE TABLE `Default`
                     (name text, GD text)''')
        except:
        #Get A List Of All The Tables
        self.cursor.execute('SELECT name FROM sqlite_master WHERE type= "table"')
        for table in self.cursor.fetchall():
            self.list.insertItem(self.cursorCount, table[0])
            self.cursorCount += 1
        self.conn.commit()
        self.conn.close()
        self.list.item(0).setSelected(True)
        self.btn = QPushButton()
        self.btn.setText("click me!")
        self.btn.clicked.connect(self.openWin)
        winWidget = QWidget()
        self.setCentralWidget(winWidget)
        layout = QVBoxLayout()
        layout.addWidget(self.list)
        layout.addWidget(self.btn)
        winWidget.setLayout(layout)
    def openWin(self):
        self.win = SecondWindow()
        self.win.show()
app = QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec_()
希望得到任何帮助