Sqlite3 Tutorial Query Python Fixed [OFFICIAL]

import sqlite3
import os
all_users = query_all_users()
for user in all_users:
print(user)
john = find_user_by_username("john_doe")
print(f"Found: john")
young_users = get_users_by_age(25, 5)
print(f"Young users: young_users")

Here’s a complete, fixed script that incorporates all best practices: sqlite3 tutorial query python fixed

import sqlite3
DB_NAME = "tasks.db"
def init_db():
with sqlite3.connect(DB_NAME) as conn:
cursor = conn.cursor()
cursor.execute("""
CREATE TABLE IF NOT EXISTS tasks (
id INTEGER PRIMARY KEY AUTOINCREMENT,
title TEXT NOT NULL,
completed INTEGER DEFAULT 0
)
""")
def add_task(title):
with sqlite3.connect(DB_NAME) as conn:
cursor = conn.cursor()
cursor.execute("INSERT INTO tasks (title) VALUES (?)", (title,))
print(f"Task 'title' added.")
def list_tasks():
with sqlite3.connect(DB_NAME) as conn:
conn.row_factory = sqlite3.Row
cursor = conn.cursor()
cursor.execute("SELECT * FROM tasks")
for row in cursor.fetchall():
status = "✓" if row["completed"] else "✗"
print(f"row['id']. row['title'] [status]") import sqlite3 import os all_users = query_all_users() for
def complete_task(task_id):
with sqlite3.connect(DB_NAME) as conn:
cursor = conn.cursor()
cursor.execute("UPDATE tasks SET completed = 1 WHERE id = ?", (task_id,))
if cursor.rowcount == 0:
print(f"Task task_id not found.")
else:
print(f"Task task_id completed.")
def delete_task(task_id):
with sqlite3.connect(DB_NAME) as conn:
cursor = conn.cursor()
cursor.execute("DELETE FROM tasks WHERE id = ?", (task_id,))
print(f"Task task_id deleted.") if cursor.rowcount else print("Not found.")
if name == "main":
init_db()
while True:
print("\n1. Add task\n2. List tasks\n3. Complete task\n4. Delete task\n5. Exit")
choice = input("Choose: ")
if choice == "1":
add_task(input("Title: "))
elif choice == "2":
list_tasks()
elif choice == "3":
complete_task(int(input("Task ID: ")))
elif choice == "4":
delete_task(int(input("Task ID: ")))
elif choice == "5":
break

Run this script. It will create tasks.db, persist data, and handle queries safely.

def close_connection(): if conn: conn.close() print("Database connection closed")

def transactional_operation(): try: with sqlite3.connect('my_database.db') as conn: cursor = conn.cursor()

        cursor.execute("UPDATE users SET age = age + 1 WHERE age < 30")
        cursor.execute("DELETE FROM users WHERE age > 100")
# If any error occurs, all changes are rolled back
except sqlite3.Error as e:
    print(f"Database error: e")

builder = SafeQueryBuilder("SELECT * FROM users") builder.add_condition("age", ">=", 21) builder.add_condition("city", "=", "New York") query, params = builder.build()

with get_db_connection() as conn: cursor = conn.cursor() cursor.execute(query, params) results = cursor.fetchall()