Sqlite3 Tutorial Query Python Fixed

cursor.execute("UPDATE users SET age = age + 1 WHERE age < 30") cursor.execute("DELETE FROM users WHERE age > 100")

conn = sqlite3.connect('corrupt.db') with open('dump.sql', 'w') as f: for line in conn.iterdump(): f.write(line + '\n') conn.close() # then recreate from dump new_conn = sqlite3.connect('recovered.db') new_conn.executescript(open('dump.sql').read())

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(1, 'John Doe', 'john@example.com') (2, 'Jane Doe', 'jane@example.com') (3, 'Bob Smith', 'bob@example.com')

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]") cursor

: For operations that modify data (like INSERT or UPDATE ), you must call connection.commit() to save the changes permanently.

Parameterized queries ( ? ) only work for values. If you need to make table names or column names dynamic based on user input, placeholders will cause syntax errors. Common Mistake: Putting Placeholders on Table Names ) only work for values

You already have everything you need – Python’s standard library includes sqlite3 . Let’s create a sample database to work with.

demonstrate_fetch_methods()

Let’s fix those permanently.

Mastering Python SQLite3: A Fixed Guide to Querying Databases