This page provides a comprehensive guide to using SQLite with Flask, focusing on the basics of database operations such as creating, querying, and updating data.

Installation

Before you begin, make sure you have Flask installed. You can install Flask using pip:

pip install flask

SQLite with Flask

SQLite is a lightweight database that is perfect for small applications and development purposes. It is also easy to set up and manage.

Database Setup

To use SQLite with Flask, you'll need to create a SQLite database. You can do this by creating a new file with a .db extension. Here is an example of a simple SQLite database file:

CREATE TABLE users (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    username TEXT NOT NULL,
    email TEXT NOT NULL
);

Flask Model

In Flask, you can use SQLAlchemy to define models that correspond to your database tables. Here is an example of a Flask model for the users table:

from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///site.db'
db = SQLAlchemy(app)

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(20), unique=True, nullable=False)
    email = db.Column(db.String(120), unique=True, nullable=False)

Adding Data

To add data to your database, you can use the session object provided by SQLAlchemy:

new_user = User(username='john_doe', email='john@example.com')
db.session.add(new_user)
db.session.commit()

Querying Data

You can query data from your database using the session.query() method:

user = User.query.filter_by(username='john_doe').first()
print(user.email)

Updating Data

To update data in your database, you can modify the object and commit the session:

user.email = 'new_email@example.com'
db.session.commit()

Deleting Data

To delete data from your database, you can use the delete() method:

user = User.query.filter_by(username='john_doe').first()
db.session.delete(user)
db.session.commit()

Further Reading

For more information on Flask and SQLite, please refer to the following resources:

图片示例

SQLite 数据库结构示意图：

SQLite Structure