Add Persistent To-Do List with SQLite DB

sqlite_todo_list/README.md

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+# Persistent To-Do List (with SQLite)
+
+This is a simple but powerful command-line to-do list application that **saves your tasks permanently** using Python's built-in `sqlite3` database.
+
+## Description
+
+Unlike simple in-memory scripts, this to-do list creates a small database file (`todo.db`) in the same directory. Any tasks you add are saved to this database. You can close the script, turn off your computer, and when you run it again, your tasks will still be there.
+
+## Features
+
+* **Persistent Storage:** Uses `sqlite3` to save tasks.
+* **Add Tasks:** Add new items to your list.
+* **Remove Tasks:** Remove items by their unique ID.
+* **List Tasks:** View all your current tasks, numbered by ID.
+* **Database Creation:** Automatically creates the `todo.db` file and `tasks` table on first run.
+
+## How to Run
+
+1.  Ensure you have Python 3 installed.
+2.  Run the script from your terminal:
+    ```sh
+    python todo_list_db.py
+    ```
+3.  A `todo.db` file will be created in the directory to store your tasks.
+4.  Follow the on-screen menu (1-4) to manage your list.
+
+## Modules Used
+
+* **`sqlite3`**: (Python's built-in module for an on-disk SQL database)
+* **`sys`**: (Built-in module for exiting the script on a critical error)

sqlite_todo_list/todo_list_db.py

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+import sqlite3
+import sys
+
+# The name of the database file
+DB_NAME = "todo.db"
+
+def initialize_db(conn):
+    """Creates the 'tasks' table if it doesn't already exist."""
+    try:
+        cursor = conn.cursor()
+        # Use 'IF NOT EXISTS' to safely run this every time
+        cursor.execute("""
+        CREATE TABLE IF NOT EXISTS tasks (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            description TEXT NOT NULL
+        );
+        """)
+        conn.commit()
+        print("Database initialized.")
+    except Exception as e:
+        print(f"Error initializing database: {e}")
+        sys.exit(1)
+
+def add_task(conn):
+    """Adds a new task to the database."""
+    desc = input("Enter the task description: ")
+    if not desc:
+        print("Task description cannot be empty.")
+        return
+
+    cursor = conn.cursor()
+    cursor.execute("INSERT INTO tasks (description) VALUES (?)", (desc,))
+    conn.commit()
+    print(f"Added task: '{desc}'")
+
+def remove_task(conn):
+    """Removes a task from the database by its ID."""
+    list_tasks(conn, quiet=True) # Show the list first
+    try:
+        task_id = int(input("Enter the task ID to remove: "))
+        cursor = conn.cursor()
+        # Use 'changes()' to see if a row was actually deleted
+        cursor.execute("DELETE FROM tasks WHERE id = ?", (task_id,))
+        if cursor.rowcount == 0:
+            print(f"No task found with ID {task_id}.")
+        else:
+            conn.commit()
+            print(f"Removed task {task_id}.")
+    except ValueError:
+        print("Invalid ID. Please enter a number.")
+
+def list_tasks(conn, quiet=False):
+    """Lists all current tasks in the database."""
+    cursor = conn.cursor()
+    cursor.execute("SELECT id, description FROM tasks ORDER BY id")
+    rows = cursor.fetchall()
+
+    if not rows:
+        if not quiet:
+            print("\nYour to-do list is empty.")
+    else:
+        print("\n--- Your To-Do List ---")
+        for row in rows:
+            print(f"  [{row[0]}] {row[1]}") # e.g., [1] Buy milk
+
+def main():
+    """Main application loop."""
+    # 'with' statement handles connection closing
+    with sqlite3.connect(DB_NAME) as conn:
+        initialize_db(conn)
+
+        while True:
+            print("\n--- Persistent To-Do List ---")
+            print("1. List tasks")
+            print("2. Add task")
+            print("3. Remove task")
+            print("4. Quit")
+            choice = input("Enter your choice (1-4): ")
+
+            if choice == '1':
+                list_tasks(conn)
+            elif choice == '2':
+                add_task(conn)
+            elif choice == '3':
+                remove_task(conn)
+            elif choice == '4':
+                print("Goodbye!")
+                break
+            else:
+                print("Invalid choice. Please enter a number from 1 to 4.")
+
+if __name__ == "__main__":
+    main()