Python-SQL-Practice-Prep

A structured refresher on Python and SQLite3 fundamentals, designed to shake off the rust and build a foundation for creating an SQL Learning Tool for High School Computer Science learners.

Overview

This repository contains three progressive warm-up exercises that transition from pure Python logic to database integration, culminating in a GUI foundation. These tasks directly inform the architecture of an interactive SQL practice tool for students.

Prerequisites

• Python 3.x
• SQLite3 (comes bundled with Python)
• CustomTkinter (for task 3)

pip install customtkinter

The Warm-up Trilogy

Three escalating challenges that build each other, moving from in-memory data structures to presistent storage then adding a graphical intergace.

Task 1: Pure Python Logic

Goal: Demostrate proficiency with data structures and control flow without database complexity.

The Task: Build a student management system using a list of dictionaries.

Requirements:

• Function to add a student (name and grade)
• Function to display all students
• Function to filter and display students with grades above 50

Key Concepts:

• Functions and scope
• Lists and dictionary manipulation
• Conditionals and loops

This task matters because it isolates Python fundamentals before intrducing database complexity. If your logic breaks here, it'll break later-fix it fist!

Task 2: The SQL Handshake

Goal: Re-establish connection to SQLite3 and understand basic CRUD operations.

The Task: Migrate the Task 1 logic to use a persistent school.db database file.

Requirements:

• Create a students table with appropriate schema
• Insert at least 3 rows of data programatically
• Execute a SELECT query and display results to console

Critical commands to remember:

db_connection.commit() # Otherwise your data will just into 'limbo'
my_cursor.execute(<sql>)    # Your SQL interface

This task matters because it bridges the gap between temporary Python data structures and persistent SQL storage. Many beginners forget commmit() - you'll remember it now!

Task 3: The GUI Skeleton

Goal: Prove that modern Python GUIs are approachable and powerful.

The Task: Create a responsive window with user and dynamic feedback.

Requirements:

• Entry box for user input
• Button that triggers an action
• Label that updates with the entered text
• Use CustomTkinter (not standard Tkinter)

Why CustomTkinter?

• Modern, clean appearance out of the box
• Class-based architecture encourages organized code
• Direct foundation for the SQL tool (SQL input box + run button)

This task matters because it is the exact interaction pattern my SQL Learning Tool will use - student types SQL --> click button --> sees results

Project Structure

Python-SQL-Practice-Prep/
|-- ThePurePythonLogic.py   # List of dictionarie implemention
|-- TheSQLiteHandshake.py   # Database integration
|-- gui_skeleton.py         # CustomTkinter interface
|-- school.db               # Generated SQLite database (Task 2)

Lessons Learned

1. Defensive Programming (The Safety Net)

• Try/Exept Blocks: I learnt how to prevent my application from craching when a user makes a mistake. By wrapping risky code (like int(input())) in a try block, I can catch errors like ValueError and provide helpful feedback instead of a crash.
• Specific Error Catching: I realized it's better to catch a specific error than a general one, so I don't accidetally hide bigger bugs in my code.

2. Database Security (The Gold Standard)

• SQL Injection Prevention: I learnt why String Concatenation (f-strings) is dangerous for database queries.
• Parameterized Queries: I implemented the ? placeholder system. This sanitizes user input, ensuring that a student's practice query doesn't accidentally delete the entire database.

3. Modern GUI Architecture

• CustomTkinter vs Standard Tkinter: I moved from the older. "blocky" look of standard Tkinter to a modern, themed interface.
• The Grid System: I mastered the Graph Paper approach to layout -- using rows, columns and sticky properties to make sure the UI looks professional and stays organized when resized.
• WIdget Control: I learned how to get data from a CTkTextbox using specific coordinated ("1.0", "end-1c") and how to confugure labels and boxes to update the user user on the fly.

Resources

• SQLite3 Python Documentation
• CustomTkinter Documentation
• SQL Tutorial

License

MIT - Use freely for personal learning or classroom instruction.