How do you connect to a SQL database in python? (AI)

Question 1

What Python standard governs database connections?

Answer 1

The Python Database API Specification (DBAPI), usually referred to as PEP 249.

Question 2

What Python module is used for connecting to SQLite databases?

Answer 2

The built-in sqlite3 module.

Question 3

What is the first object you must create to interact with a database?

Answer 3

The Connection object.

Question 4

Example: Establishing a connection to a SQLite file named ‘app.db’

Answer 4

conn = sqlite3.connect('app.db')

Question 5

What object do you create from the connection to execute SQL queries?

Answer 5

The Cursor object.

Question 6

Example: Creating a cursor object

Answer 6

cursor = conn.cursor()

Question 7

How do you execute an SQL command (like CREATE TABLE)?

Answer 7

Use the cursor’s execute() method: cursor.execute("CREATE TABLE users (id, name)")

Question 8

How do you ensure changes (like INSERT or UPDATE) are permanently saved to the database?

Answer 8

Call the commit() method on the connection object: conn.commit()

Question 9

How do you run a SELECT query and retrieve one result row?

Answer 9

Use the fetchone() method on the cursor.

Question 10

How do you run a SELECT query and retrieve all result rows?

Answer 10

Use the fetchall() method on the cursor.

Question 11

How do you safely close the connection after you are done?

Answer 11

Call the close() method on both the cursor and the connection: cursor.close() and conn.close()

Question 12

What keyword is often used to ensure connection and cursor objects are closed automatically?

Answer 12

The with keyword (used for context management).

Question 13

Example: Connection using the with statement

Answer 13

with sqlite3.connect('app.db') as conn:

Question 14

What common third-party library is often used for connecting to PostgreSQL?

Answer 14

psycopg2

Question 15

What common third-party library is often used for connecting to MySQL?

Answer 15

mysql-connector-python or PyMySQL

Question 16

Why should you never use f-strings to insert data into an SQL query?

Answer 16

It exposes the application to SQL Injection attacks.

Question 17

How should you pass variable data into an SQL query safely?

Answer 17

Use question marks (?) as placeholders in the query string and pass the variables as a tuple to the execute() method.

Question 18

Example: Safe insertion of a name variable

Answer 18

name = 'Alice'\ncursor.execute("INSERT INTO users VALUES (?, 'password')", (name,))

Question 19

What is an ORM (Object-Relational Mapper)?

Answer 19

A library (like SQLAlchemy) that allows you to interact with your database using object-oriented code instead of raw SQL.

Question 20

What happens if you forget to call conn.commit() after an INSERT statement?

Answer 20

The change will not be saved to the database