Hopefully, you figured out how to solve the challenge from the last lesson, as a review, here's a summary of some of the things we did:

Create a New Database

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = "sqlite:///<name of database>.db"
db = SQLAlchemy(app)

Create a New Table

class Book(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String(250), unique=True, nullable=False)
    author = db.Column(db.String(250), nullable=False)
    rating = db.Column(db.Float, nullable=False
db.create_all()

In addition to these things, the most crucial thing to figure out when working with any new database technology is how to CRUD data records.

Create

Read

Update

Delete

So, let's go through each of these using SQLite and SQLAlchemy:

Create A New Record

new_book = Book(id=1, title="Harry Potter", author="J. K. Rowling", rating=9.3)
db.session.add(new_book)
db.session.commit()

NOTE: When creating new records, the primary key fields is optional. you can also write:

new_book = Book(title="Harry Potter", author="J. K. Rowling", rating=9.3)

the id field will be auto-generated.

Read All Records

all_books = session.query(Book).all()

Read A Particular Record By Query

book = Book.query.filter_by(title="Harry Potter").first()

Update A Particular Record By Query

book_to_update = Book.query.filter_by(title="Harry Potter").first()
book_to_update.title = "Harry Potter and the Chamber of Secrets"
db.session.commit()  

Update A Record By PRIMARY KEY

book_id = 1
book_to_update = Book.query.get(book_id)
book_to_update.title = "Harry Potter and the Goblet of Fire"
db.session.commit()  

Delete A Particular Record By PRIMARY KEY

book_id = 1
book_to_delete = Book.query.get(book_id)
db.session.delete(book_to_delete)
db.session.commit()

You can also delete by querying for a particular value e.g. by title or one of the other properties.