Here's a well-structured article on using Flutter Sqflite:

Using SQLite with Flutter: A Step-by-Step Guide

When building mobile applications, one of the most crucial aspects is how to store and retrieve data locally. In this tutorial, we will demonstrate how to create a simple Flutter app that uses SQLite for storing user details.

What is SQLite?

SQLite is a lightweight database engine that allows us to store structured data on our devices. It is widely used in mobile applications due to its ease of use and flexibility. In the context of Flutter, SQLite can be used to persist data even after the application is closed or the device restarted.

Getting Started with SQLite in Flutter

To get started with SQLite in Flutter, we need to install the `sqflite` package using the following command:

```

flutter pub add sqflite

```

Once installed, let's create a new Flutter project and name it `sqlite_demo`. We will then navigate to the project directory and open it in our text editor.

Creating the Database

In this tutorial, we will create a database that can store user details. To do this, we need to define the schema of the database using SQL queries. In our case, we have a simple table called `users` with three columns: `id`, `name`, and `email`.

```dart

import 'package:flutter/material.dart';

import 'package:sqflite/sqflite.dart';

class DatabaseHelper {

static final DatabaseHelper _instance = DatabaseHelper.internal();

static Database _db;

factory DatabaseHelper() => _instance;

DatabaseHelper.internal();

Future get db async {

if (_db != null) return _db;

_db = await initDB();

return _db;

}

initDB() async {

Directory documentsDirectory = await getApplicationDocumentsDirectory();

String path = join(documentsDirectory.path, 'user_data.db');

var theDb = await openDatabase(path);

return theDb;

}

```

CRUD Operations

Now that we have created our database, let's define the CRUD (Create, Read, Update, Delete) operations for our `users` table. We will use the following methods:

* `insert()`: To insert a new user into the database

* `update()`: To update an existing user in the database

* `query()`: To retrieve all users from the database

* `delete()`: To delete a user from the database

Here is how we can implement these methods:

```dart

class DatabaseHelper {

// ...

Future insert(User user) async {

final Database db = await db;

var result = await db.insert('users', user.toMap());

return result;

}

Future queryUser(int id) async {

final Database db = await db;

var result = await db.query('users', where: 'id = ?', whereArgs: 'id');

if (result.isNotEmpty) {

return User.fromMap(result.first);

}

return null;

}

Future update(User user) async {

final Database db = await db;

var result = await db.update('users', user.toMap(), where: 'id = ?', whereArgs: 'user.id');

return result;

}

Future delete(int id) async {

final Database db = await db;

var result = await db.delete('users', where: 'id = ?', whereArgs: 'id');

return result;

}

```

In this tutorial, we have demonstrated how to use SQLite with Flutter to store and retrieve data locally. We have defined the schema of our database using SQL queries and implemented CRUD operations for our `users` table.

We hope you found this tutorial helpful in getting started with SQLite in your own Flutter projects. Happy coding!

Flutter sqflite