SQLite Overview and Setup

Introduction to SQLite

• SQLite is useful for database functionality without requiring a full-fledged database system like MySQL or Postgres.
• Ideal for small to medium-sized applications, testing, and prototyping.
• Part of the Python standard library, hence requires no installation.
• Database can be a simple file or an in-memory database.

Assumptions

• Assumes basic knowledge of SQL for the tutorial.

Sample Code

• Uses sample code from an object-oriented series, specifically focusing on an Employee class.
• The main file for SQLite demonstration is sqlite_demo.py.

Working with SQLite in Python

Setting Up Connection

• Import SQLite3 with import sqlite3.
• Create a connection object using sqlite3.connect(), which can connect to a file or create an in-memory database.
• Example: conn = sqlite3.connect('employee.db') creates a file-based database, whereas conn = sqlite3.connect(':memory:') creates an in-memory database.

Creating a Cursor

• Create a cursor using cursor = conn.cursor() to execute SQL commands.

Creating a Table

• Use CREATE TABLE SQL command to create tables.
• Example table schema: id, first_name, last_name, and pay.
• Data types: TEXT, INTEGER, etc.

Inserting Data

• Use INSERT INTO SQL command to add data.
• Example: cursor.execute("INSERT INTO employees VALUES (?, ?, ?)", (first_name, last_name, pay)).
• Commit changes with conn.commit().

Querying Data

• Use SELECT SQL command to retrieve data.
• Example: cursor.execute("SELECT * FROM employees WHERE last=?", (last_name,)).
• Fetch results using fetchone(), fetchmany(size), or fetchall().*

Using Placeholders

• Prevent SQL injection by using placeholders (? or :variable) in queries.
• Use tuples or dictionaries to pass values.

Advanced Usage

Using Context Managers

• Use with conn: to manage transactions, automatically committing or rolling back.

Example Functions

• Create functions for common operations: insert_employee, get_employee_by_name, update_pay, remove_employee.

Prototyping with In-Memory Database

• Use in-memory databases for testing, which start fresh on every run.

Closing the Connection

• Always close the connection with conn.close().

Additional Resources

Further Learning

• Explore bulk inserts and advanced SQLite features.
• Consider using SQLite with SQLAlchemy for ORM capabilities.

Community Support

• Engage with the community for questions and further assistance.

Supporting the Creator

• Options include liking, sharing, and supporting through Patreon.

Conclusion

• SQLite offers a lightweight, easy-to-use solution for database management in small to medium applications.