**Course Title:** Flutter Development: Build Beautiful Mobile Apps **Section Title:** Working with Databases and Local Storage **Topic:** Build a Flutter app that stores and retrieves data using SQLite.(Lab topic) **Introduction** In this lab topic, we will learn how to build a Flutter app that stores and retrieves data using SQLite. SQLite is a lightweight, self-contained database that is widely used in mobile and web applications. In this topic, we will cover the basics of SQLite, how to use it in Flutter, and how to implement CRUD (Create, Read, Update, Delete) operations. **What is SQLite?** SQLite is a relational database management system (RDBMS) that is designed to be lightweight and self-contained. It is a single file database that can be embedded in an application, making it easy to use and manage. SQLite is widely used in mobile and web applications because it is: * Lightweight: SQLite is a small database that can be embedded in an application, making it easy to use and manage. * Self-contained: SQLite is a single file database that can be embedded in an application, making it easy to use and manage. * Relational: SQLite is a relational database that allows you to create tables, relationships, and queries. **Setting up SQLite in Flutter** To use SQLite in Flutter, you need to add the `sqlite3` package to your project. You can do this by adding the following line to your `pubspec.yaml` file: ```yml dependencies: flutter: sdk: flutter sqlite3: ^1.3.0 ``` Then, run `flutter pub get` to get the package. **Creating a SQLite Database** To create a SQLite database in Flutter, you need to use the `sqlite3` package. You can do this by creating a new instance of the `Database` class and calling the `open` method: ```dart import 'package:sqflite/sqflite.dart'; Future<Database> _openDatabase() async { return await openDatabase( 'database.db', version: 1, onCreate: (db, version) { // Create the table db.execute(''' CREATE TABLE users ( id INTEGER PRIMARY KEY, name TEXT NOT NULL, email TEXT NOT NULL ) '''); }, ); } ``` **Inserting Data into the Database** To insert data into the database, you need to use the `insert` method: ```dart Future<void> _insertUser(User user) async { final db = await _openDatabase(); await db.insert('users', user.toJson()); } ``` **Retrieving Data from the Database** To retrieve data from the database, you need to use the `select` method: ```dart Future<List<User>> _getUsers() async { final db = await _openDatabase(); return db.select('users').map((map) => User.fromJson(map['id'], map['name'], map['email'])).toList(); } ``` **Updating Data in the Database** To update data in the database, you need to use the `update` method: ```dart Future<void> _updateUser(User user) async { final db = await _openDatabase(); await db.update('users', user.toJson(), where: 'id = ?', whereArgs: [user.id]); } ``` **Deleting Data from the Database** To delete data from the database, you need to use the `delete` method: ```dart Future<void> _deleteUser(User user) async { final db = await _openDatabase(); await db.delete('users', where: 'id = ?', whereArgs: [user.id]); } ``` **Putting it all Together** Here is the complete code for the lab topic: ```dart import 'package:flutter/material.dart'; import 'package:sqflite/sqflite.dart'; import 'package:your_app/models/user.dart'; class SQLiteLab extends StatefulWidget { @override _SQLiteLabState createState() => _SQLiteLabState(); } class _SQLiteLabState extends State<SQLiteLab> { final _users = <User>[]; Future<Database> _openDatabase() async { return await openDatabase( 'database.db', version: 1, onCreate: (db, version) { // Create the table db.execute(''' CREATE TABLE users ( id INTEGER PRIMARY KEY, name TEXT NOT NULL, email TEXT NOT NULL ) '''); }, ); } Future<void> _insertUser(User user) async { final db = await _openDatabase(); await db.insert('users', user.toJson()); } Future<List<User>> _getUsers() async { final db = await _openDatabase(); return db.select('users').map((map) => User.fromJson(map['id'], map['name'], map['email'])).toList(); } Future<void> _updateUser(User user) async { final db = await _openDatabase(); await db.update('users', user.toJson(), where: 'id = ?', whereArgs: [user.id]); } Future<void> _deleteUser(User user) async { final db = await _openDatabase(); await db.delete('users', where: 'id = ?', whereArgs: [user.id]); } @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar( title: Text('SQLite Lab'), ), body: Center( child: Column( mainAxisAlignment: MainAxisAlignment.center, children: <Widget>[ ElevatedButton( onPressed: () async { final db = await _openDatabase(); final users = await db.select('users').map((map) => User.fromJson(map['id'], map['name'], map['email'])).toList(); setState(() { _users = users; }); }, child: Text('Get Users'), ), ElevatedButton( onPressed: () async { final db = await _openDatabase(); final user = User(1, 'John Doe', 'john@example.com'); await _insertUser(user); }, child: Text('Insert User'), ), ElevatedButton( onPressed: () async { final db = await _openDatabase(); final users = await _getUsers(); setState(() { _users = users; }); }, child: Text('Get Users'), ), ElevatedButton( onPressed: () async { final db = await _openDatabase(); final user = User(1, 'John Doe', 'john@example.com'); await _updateUser(user); }, child: Text('Update User'), ), ElevatedButton( onPressed: () async { final db = await _openDatabase(); final user = User(1, 'John Doe', 'john@example.com'); await _deleteUser(user); }, child: Text('Delete User'), ), Text('Users: ${_users.length}'), ListView.builder( itemCount: _users.length, itemBuilder: (context, index) { return ListTile( title: Text(_users[index].name), subtitle: Text(_users[index].email), ); }, ), ], ), ), ); } } ``` **Conclusion** In this lab topic, we learned how to build a Flutter app that stores and retrieves data using SQLite. We covered the basics of SQLite, how to use it in Flutter, and how to implement CRUD operations. We also put it all together by creating a complete app that demonstrates the use of SQLite in Flutter. **Exercise** 1. Create a new Flutter project and add the `sqlite3` package to your `pubspec.yaml` file. 2. Create a new SQLite database and create a table called `users` with columns `id`, `name`, and `email`. 3. Insert some data into the `users` table. 4. Retrieve the data from the `users` table and display it in a list view. 5. Update some data in the `users` table. 6. Delete some data from the `users` table. **Leave a comment or ask for help if you have any questions or need further clarification on any of the concepts covered in this lab topic.**