This will display a QComboBox widget with three items. When the user selects an item, the currentIndexChanged signal will emit, allowing the application to respond to the user's selection. Another code example: To populate a QComboBox widget using data from an SQLite database, first, create a database connection, retrieve data from the database, add the data to a list and then to the QComboBox widget.python import sqlite3 from PyQt5.QtWidgets import QApplication, QWidget, QComboBox app = QApplication([]) conn = sqlite3.connect("example.db") cursor = conn.cursor() cursor.execute("SELECT * FROM example") rows = cursor.fetchall() items = [row[1] for row in rows] window = QWidget() combo = QComboBox(window) for item in items: combo.addItem(item) combo.show() window.show() app.exec_() ``` This will display a QComboBox widget populated with items from a database table.