PyQT5 / QT Designer - Многопоточность с сигналом / слотами

Я написал приложение PyQt5, которое ищет вводимые пользователем данные в базе данных SQL. Все работает, но мне не удалось добавить рабочий поток для обработки процесса поиска и предотвращения зависания приложения. Я использую QT Designer для генерации кода для пользовательского интерфейса, который состоит из главного окна, полей QLineEdit для ввода и QPushButton для начала поиска. Что касается индикатора выполнения (и кнопки «Отмена», чтобы остановить поиск), я рассматриваю два варианта: закрепить его в главном окне или отобразить в диалоговом окне. В классе QMainWindow я определил функцию для захвата вводимых пользователем данных (set_validators) и функцию для обработки поиска и отображения результатов (save_pushing). Я понимаю основы сигнала / слота, я просмотрел несколько примеров, но я просто не уверен, как все это собрать. Я думаю, что отчасти проблема заключается в области видимости переменных. Может ли кто-нибудь дать общее руководство?

QA1, QA2, QA3

#!/usr/bin/env python

import pyodbc
import sys

from PyQt5.QtWidgets import QMainWindow, QApplication, QTableWidgetItem, QMessageBox
from PyQt5.QtGui import QRegExpValidator
from PyQt5.QtCore import QRegExp
from PyQt5 import uic

from ui_pysearch import Ui_pySearch

class pySearchMain(QMainWindow):
    def __init__(self):
        QMainWindow.__init__(self)
        self.ui = Ui_pySearch()
        self.ui.setupUi(self)
        self.ui.tableWidget_ResultsIncident.setHorizontalHeaderLabels(["A", "B", "C"])
        self.ui.tableWidget_ResultsCompany.setHorizontalHeaderLabels(["A", "B", "C"])

        self._set_validators()
        self.ui.Button_Search.clicked.connect(self._save_pushed)

    def _set_validators(self):
        reg_ex = QRegExp(r"[A-Za-z0-9]{0,6}")
        val_company_custid = QRegExpValidator(reg_ex, self.ui.Input_lineEdit_CompanyPIN)
        self.ui.Input_lineEdit_CompanyPIN.setValidator(val_company_custid)

        reg_ex = QRegExp(r"[A-Za-z ]{0,25}")
        val_company_name = QRegExpValidator(reg_ex, self.ui.Input_lineEdit_CompanyName)
        self.ui.Input_lineEdit_CompanyName.setValidator(val_company_name)

        reg_ex = QRegExp(r"[A-Za-z ]{0,25}")
        val_incident_service = QRegExpValidator(reg_ex, self.ui.Input_lineEdit_IncidentService)
        self.ui.Input_lineEdit_IncidentService.setValidator(val_incident_service)

    def _save_pushed(self):

        self.ui.tableWidget_ResultsIncident.clearContents()
        self.ui.tableWidget_ResultsCompany.clearContents()

        Company_CustID = self.ui.Input_lineEdit_CompanyPIN.text()
        Company_Name = self.ui.Input_lineEdit_CompanyName.text()
        Incident_Service = self.ui.Input_lineEdit_IncidentService.text()

        Set_Company_RecID = set()
        Set_Company_CustID = set()
        Set_Company_CustID_Substring = set()
        Set_Company_Name = set()
        Set_Company_Name_Substring = set()
        Set_IncidentNumber_CompanyName = set()
        Set_IncidentNumber_Service = set()

        Match_Input_lineEdit = 1
        Match_RecID_CompanyCustID = -1
        Match_RecID_CompanyName = -1

        if len(str(Company_CustID)) == 6:
            with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:
                SearchCursor = DB_Connect.cursor()
                SearchCursor.execute("select RecId, CustID, Name from Company")
                for row in SearchCursor.fetchall():
                    if str(row[1]).lower() == str(Company_CustID).lower():
                        Match_RecID_CompanyCustID = row[0]
                        Set_Company_RecID.add(str(row[1]))
        if len(str(Company_CustID)) > 1:
            with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:
                SearchCursor = DB_Connect.cursor()
                SearchCursor.execute("select RecId, CustID, Name from Company")
                for row in SearchCursor.fetchall():
                    if str(row[1]).lower().rfind(str(Company_CustID).lower()) != -1:
                        Set_Company_CustID_Substring.add(row[0])
                        Set_Company_RecID.add(str(row[1]))
        if len(str(Company_Name)) > 2:
            with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:
                SearchCursor = DB_Connect.cursor()
                SearchCursor.execute("select RecId, CustID, Name from Company")
                for row in SearchCursor.fetchall():
                    if str(row[2]).lower() == str(Company_Name).lower():
                        Match_RecID_CompanyName = row[0]
                        Set_Company_RecID.add(str(row[1]))
                    if str(row[2]).lower().rfind(str(Company_Name).lower()) != -1:
                        Set_Company_Name_Substring.add(row[0])
                        Set_Company_RecID.add(str(row[1]))
        if Match_RecID_CompanyCustID != -1:
            with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:
                SearchCursor = DB_Connect.cursor()
                SearchCursor.execute("select IncidentNumber from Incident")
                for row in SearchCursor.fetchall():
                    if row[0] == Match_RecID_CompanyCustID:
                        Set_Company_CustID.add(int(row[0]))
        if Match_RecID_CompanyName != -1:
            with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:
                SearchCursor = DB_Connect.cursor()
                SearchCursor.execute("select IncidentNumber, CompanyLink_RecID from Incident")
                for row in SearchCursor.fetchall():
                    if row[1] == Match_RecID_CompanyName:
                        Set_Company_Name.add(int(row[0]))
        if len(str(Company_Name)) > 2:
            with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:
                SearchCursor = DB_Connect.cursor()
                SearchCursor.execute("select IncidentNumber, CompanyName from Incident")
                for row in SearchCursor.fetchall():
                    if str(row[1]).lower() == str(Company_Name).lower():
                        Set_IncidentNumber_CompanyName.add(int(row[0]))
                    if str(row[1]).lower().rfind(str(Company_Name).lower()) != -1:
                        Set_IncidentNumber_CompanyName.add(int(row[0]))
        if len(Incident_Service) > 2:
            with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:
                SearchCursor = DB_Connect.cursor()
                SearchCursor.execute("select IncidentNumber, Service from Incident")
                for row in SearchCursor.fetchall():
                    if (row[1].lower()).rfind(Incident_Service.lower()) != -1:
                        Set_IncidentNumber_Service.add(int(row[0]))
        if len(Set_Company_CustID_Substring) != 0:
            with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:
                SearchCursor = DB_Connect.cursor()
                SearchCursor.execute("select IncidentNumber, CompanyLink_RecID from Incident")
                for row in SearchCursor.fetchall():
                    for Set_Company_CustID_Substring_Item in Set_Company_CustID_Substring:
                        if row[1] == Set_Company_CustID_Substring_Item:
                            Set_Company_CustID.add(int(row[0]))
        if len(Set_Company_Name_Substring) != 0:
            with pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:
                SearchCursor = DB_Connect.cursor()
                SearchCursor.execute("select IncidentNumber, CompanyLink_RecID from Incident")
                for row in SearchCursor.fetchall():
                    for Set_Company_Name_Substring_Item in Set_Company_Name_Substring:
                        if row[1] == Set_Company_Name_Substring_Item:
                            Set_Company_Name.add(int(row[0]))


        if len(Set_Company_CustID) == 0 and len(Company_CustID) != 0:
            Match_Input_lineEdit = 0
        if len(Set_Company_Name) == 0 and len(Company_Name) != 0:
            Match_Input_lineEdit = 0
        if len(Set_IncidentNumber_Service) == 0 and len(Incident_Service) != 0:
            Match_Input_lineEdit = 0
        if len(Set_IncidentNumber_CompanyName) == 0 and len(Company_Name) != 0:
            Match_Input_lineEdit = 0
            Match_Input_lineEdit = 0
        if Match_Input_lineEdit == 0:
            alert = QMessageBox()
            alert.setText('No results')
            self.ui.tableWidget_ResultsIncident.clearContents()
            self.ui.tableWidget_ResultsIncident.setRowCount(0)
            alert.exec_()
            return
        List_Of_All_Sets = [Set_Company_CustID, Set_Company_Name, Set_IncidentNumber_Service, Set_IncidentNumber_CompanyName]

        try:
            Set_Intersection = set.intersection(*(s for s in List_Of_All_Sets if s))
            if len(Set_Intersection) == 0:
                alert = QMessageBox()
                alert.setText('No results')
                self.ui.tableWidget_ResultsIncident.clearContents()
                self.ui.tableWidget_ResultsIncident.setRowCount(0)
                alert.exec_()
        except TypeError:
            alert = QMessageBox()
            alert.setText('No results')
            self.ui.tableWidget_ResultsIncident.clearContents()
            self.ui.tableWidget_ResultsIncident.setRowCount(0)
            alert.exec_()
        else:
            if self.ui.radioButton_Search_Incident.isChecked():
                self.ui.tableWidget_ResultsIncident.setRowCount(0)
                tableWidget_ResultsIncident_row_num = self.ui.tableWidget_ResultsIncident.rowCount()
                with pyodbc.connect(
                    'DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:
                    Set_Intersection_Cursor = DB_Connect.cursor()

                    Set_Intersection_Cursor.execute("select CompanyLink_RecID, IncidentNumber from Incident")
                    for Set_Intersection_Cursor_Incident_Item in Set_Intersection_Cursor.fetchall():
                        for Set_Intersection_Item in Set_Intersection:
                            if Set_Intersection_Cursor_Incident_Item[1] == Set_Intersection_Item:
                                Match_Intersection_RecID = Set_Intersection_Cursor_Incident_Item[0]

                                Set_Intersection_Cursor.execute("select RecId, CustID, Name from Company")
                                for Set_Intersection_Cursor_Company_Item in Set_Intersection_Cursor.fetchall():
                                    if Set_Intersection_Cursor_Company_Item[0] == Match_Intersection_RecID:
                                        self.ui.tableWidget_ResultsIncident.insertRow(tableWidget_ResultsIncident_row_num)
                                        self.ui.tableWidget_ResultsIncident.setItem(tableWidget_ResultsIncident_row_num, 0, QTableWidgetItem(str(Set_Intersection_Item)))
                                        self.ui.tableWidget_ResultsIncident.setItem(tableWidget_ResultsIncident_row_num, 1, QTableWidgetItem(str(Set_Intersection_Cursor_Company_Item[1])))

                                        Set_Intersection_Cursor.execute("select IncidentNumber, Priority, Service, TypeOfIncident, CellNum, CreatedDateTime, Status, TACPrime, Owner from Incident")
                                        for row in Set_Intersection_Cursor.fetchall():
                                            if row[0] == Set_Intersection_Item:
                                                self.ui.tableWidget_ResultsIncident.setItem(tableWidget_ResultsIncident_row_num, 2, QTableWidgetItem(str(row[1]))) #Priority
                                            if row[0] == Set_Intersection_Item:
                                                self.ui.tableWidget_ResultsIncident.setItem(tableWidget_ResultsIncident_row_num, 3, QTableWidgetItem(str(row[2]))) #Service

            if len(Set_Company_RecID) != 0 and self.ui.radioButton_Search_Company.isChecked():
                self.ui.tableWidget_ResultsCompany.setColumnWidth(0, 215)
                self.ui.tableWidget_ResultsCompany.setColumnWidth(1, 215)
                self.ui.tableWidget_ResultsCompany.setColumnWidth(2, 215)

                self.ui.tableWidget_ResultsCompany.setRowCount(0)
                tableWidget_ResultsCompany_row_num = self.ui.tableWidget_ResultsCompany.rowCount()
                with pyodbc.connect(
                    'DRIVER={ODBC Driver 17 for SQL Server};SERVER=ServerIP;DATABASE=Sqldbname;UID=db_username;PWD=db_password') as DB_Connect:
                    Company_RecID_Cursor = DB_Connect.cursor()

                    Company_RecID_Cursor.execute("select RecID, CustID, Name from Company")
                    for Company_RecID_Cursor_Item in Company_RecID_Cursor.fetchall():
                        for Set_Company_RecID_Item in Set_Company_RecID:
                            if Company_RecID_Cursor_Item[1] == Set_Company_RecID_Item:
                                self.ui.tableWidget_ResultsCompany.insertRow(tableWidget_ResultsCompany_row_num)
                                self.ui.tableWidget_ResultsCompany.setItem(tableWidget_ResultsCompany_row_num, 0, QTableWidgetItem(str(Set_Company_RecID_Item)))
                                self.ui.tableWidget_ResultsCompany.setItem(tableWidget_ResultsCompany_row_num, 1, QTableWidgetItem(str(Company_RecID_Cursor_Item[2])))
                                self.ui.tableWidget_ResultsCompany.setItem(tableWidget_ResultsCompany_row_num, 2, QTableWidgetItem(str(Company_RecID_Cursor_Item[0])))

if __name__ == '__main__':
    app = QApplication(sys.argv)
    main = pySearchMain()
    main.show()
    sys.exit(app.exec_())