How can I access local database on react native?

In React Native, accessing local databases typically involves using popular libraries for data storage and retrieval. The most commonly used libraries are SQLite and Realm. Below, I will detail how to use these two approaches to access local databases.

Using SQLite

SQLite is a lightweight database, ideal for mobile devices. The React Native community provides several wrapper libraries for SQLite, such as react-native-sqlite-storage.

Installation and Setup:

First, install this library:

bash
npm install react-native-sqlite-storage

Then, in your React Native project, import and use it:

javascript
import SQLite from 'react-native-sqlite-storage';

// Open or create the database
const db = SQLite.openDatabase({name: 'my.db', location: 'default'}, () => {
  console.log('Database successfully opened or created');
}, err => {
  console.error('Error opening database: ', err);
});

// Using the database
db.transaction(tx => {
  // Create table
  tx.executeSql('CREATE TABLE IF NOT EXISTS Users (id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, age INTEGER)', []);

  // Insert data
  tx.executeSql('INSERT INTO Users (name, age) VALUES (?, ?)', ['John', 30]);

  // Query data
  tx.executeSql('SELECT * FROM Users', [], (tx, results) => {
    var len = results.rows.length;
    for (let i = 0; i < len; i++) {
      let row = results.rows.item(i);
      console.log(`User ID: ${row.id}, Name: ${row.name}, Age: ${row.age}`);
    }
  });
});

Using Realm

Realm is another popular cross-platform lightweight database solution suitable for React Native. It offers richer data models and query capabilities.

Installation and Configuration:

First, install Realm:

bash
npm install realm

Using Realm:

javascript
import Realm from 'realm';

// Define the model and schema
class User extends Realm.Object {}
User.schema = {
  name: 'User',
  primaryKey: 'id',
  properties: {
    id: 'int',
    name: 'string',
    age: 'int',
  },
};

// Open the database
let realm = new Realm({schema: [User]});

// Write data
realm.write(() => {
  realm.create('User', {
    id: 1,
    name: 'John',
    age: 30,
  });
});

// Read data
let users = realm.objects('User');
console.log('Number of users:', users.length);
users.forEach(user => {
  console.log(`User ID: ${user.id}, Name: ${user.name}, Age: ${user.age}`);
});

In both approaches, you can choose the appropriate database solution based on your project's requirements and complexity. SQLite is suitable for more traditional SQL operations, while Realm provides a more modern data management approach.