Using PyQt to Display Database Data in a QTableWidget

In this tutorial, we will learn how to fetch data from a database and display it in a QTableWidget using PyQt. We will use Python as the programming language and SQLite as the database.

Step 1: Install PyQt and SQLite
Before we start, make sure you have PyQt and SQLite installed on your machine. You can install these packages using pip:

pip install PyQt5
pip install sqlite3

Step 2: Create a SQLite Database
We will create a simple SQLite database with a table called "employees" that contains three columns: id, name, and age. You can create a new database file using a SQLite client or run the following code in Python:

import sqlite3

conn = sqlite3.connect('employees.db')
c = conn.cursor()

c.execute('''CREATE TABLE employees
             (id INTEGER PRIMARY KEY, name TEXT, age INTEGER)''')

conn.commit()
conn.close()

Step 3: Populate the Database
Next, we will populate the "employees" table with some sample data. You can insert data using a SQLite client or run the following code in Python:

conn = sqlite3.connect('employees.db')
c = conn.cursor()

c.execute("INSERT INTO employees (name, age) VALUES ('Alice', 25)")
c.execute("INSERT INTO employees (name, age) VALUES ('Bob', 30)")
c.execute("INSERT INTO employees (name, age) VALUES ('Charlie', 35)")

conn.commit()
conn.close()

Step 4: Create a PyQt Application
Now, let’s create a PyQt application that fetches data from the database and displays it in a QTableWidget. Here’s the code:

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QTableWidget, QTableWidgetItem
import sqlite3

class MyWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        self.setWindowTitle("Employee Data")
        self.setGeometry(100, 100, 600, 400)

        self.tableWidget = QTableWidget(self)
        self.tableWidget.setGeometry(50, 50, 500, 300)
        self.tableWidget.setColumnCount(3)
        self.tableWidget.setHorizontalHeaderLabels(['ID', 'Name', 'Age'])

        conn = sqlite3.connect('employees.db')
        c = conn.cursor()
        c.execute("SELECT * FROM employees")
        data = c.fetchall()

        for row_num, row_data in enumerate(data):
            self.tableWidget.insertRow(row_num)
            for col_num, col_data in enumerate(row_data):
                self.tableWidget.setItem(row_num, col_num, QTableWidgetItem(str(col_data)))

        conn.close()

if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = MyWindow()
    window.show()
    sys.exit(app.exec_())

Step 5: Run the Application
Save the code in a file (e.g., main.py) and run it using Python. You should see a window with a table displaying the employee data fetched from the database.

That’s it! You have successfully displayed data in a QTableWidget from a database using PyQt. Feel free to customize the application further to meet your specific requirements.