Всплывающие списки

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QLabel, QComboBox, QVBoxLayout, QSlider
from PyQt5.QtSql     import QSqlDatabase, QSqlQuery, QSqlQueryModel, QSqlTableModel
from PyQt5.QtCore    import Qt
class Window(QWidget):
  def __init__(self):
    super().__init__(None)
    c1 = QComboBox()
    c2 = QComboBox()
    sliderText = QLabel("0")
    self.slider = QSlider(Qt.Horizontal)
    self.slider.valueChanged.connect(lambda value: sliderText.setText(str(value)))
    self.m1 = QSqlTableModel()
    self.m1.setTable("c1")
    self.m1.select()
    c1.setModel(self.m1)
    c1.currentIndexChanged.connect(self.updateC2)
    self.m2 = QSqlQueryModel()
    c2.setModel(self.m2)
    c2.currentTextChanged.connect(lambda text2: self.slider.setMaximum(int(c1.currentText()) + int(text2)))
    c1.setModelColumn(1)
    l = QVBoxLayout()
    l.addWidget(c1)
    l.addWidget(c2)
    l.addWidget(self.slider)
    l.addWidget(sliderText)
    self.setLayout(l)
  def updateC2(self, row):
    c1_id = self.m1.index(row,0).data()
    query = QSqlQuery()
    query.prepare("SELECT value FROM c2 WHERE c1_id=:c1_id;")
    query.bindValue(":c1_id", c1_id)
    query.exec_()
    self.m2.setQuery(query)
app = QApplication(sys.argv)
db = QSqlDatabase.addDatabase("QSQLITE")
db.setDatabaseName(":memory:")
db.open()
query = QSqlQuery()
query.exec_("PRAGMA foreign_keys = ON;")
query.exec_("CREATE TABLE c1 (id INTEGER PRIMARY KEY, value INTEGER);")
query.exec_("INSERT INTO c1 (id, value) VALUES (100, 5);")
query.exec_("INSERT INTO c1 (id, value) VALUES (101, 6);")
query.exec_("INSERT INTO c1 (id, value) VALUES (102, 7);")
query.exec_("CREATE TABLE c2 (id INTEGER PRIMARY KEY, value INTEGER, c1_id INTEGER,"
            "FOREIGN KEY (c1_id)  REFERENCES c1(id));")
query.exec_("INSERT INTO c2 (id, value, c1_id) VALUES (100, 10, 100);")
query.exec_("INSERT INTO c2 (id, value, c1_id) VALUES (101, 10, 101);")
query.exec_("INSERT INTO c2 (id, value, c1_id) VALUES (102, 20, 101);")
query.exec_("INSERT INTO c2 (id, value, c1_id) VALUES (103, 10, 102);")
query.exec_("INSERT INTO c2 (id, value, c1_id) VALUES (104, 20, 102);")
query.exec_("INSERT INTO c2 (id, value, c1_id) VALUES (105, 30, 102);")
window = Window()
window.show()
window.resize(300,200)
sys.exit(app.exec_())