immutable-database-mariasql

const { Client } = require('immutable-database-mariasql'); const client = new Client({ host: process.env.DB_HOST ?? 'localhost', user: process.env.DB_USER ?? 'root', password: process.env.DB_PASSWORD ?? '', db: process.env.DB_NAME ?? 'test_db', charset: 'utf8mb4' }); async function runImmutableExample() { try { await client.connect(); console.log('Connected to MariaDB/MySQL.'); // Create a table for immutable logs if it doesn't exist (example for 'immutable' pattern) await client.query(` CREATE TABLE IF NOT EXISTS audit_log ( id INT AUTO_INCREMENT PRIMARY KEY, action VARCHAR(255) NOT NULL, user_id INT NOT NULL, timestamp DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP, data JSON, superseded_id INT NULL ); `); console.log('Ensured audit_log table exists.'); // Demonstrate 'immutable' insert: adding a new record instead of updating const insertResult = await client.query( 'INSERT INTO audit_log (action, user_id, data) VALUES (?, ?, ?)', ['USER_CREATED', 101, JSON.stringify({ username: 'alice', email: 'alice@example.com' })] ); console.log('New user log entry:', insertResult.info.affectedRows); // When data conceptually 'changes', a new log entry is created. // The previous entry can be referenced as 'superseded'. const previousLog = (await client.query('SELECT id FROM audit_log WHERE user_id = ? ORDER BY id DESC LIMIT 1', [101]))[0]; const updateLogResult = await client.query( 'INSERT INTO audit_log (action, user_id, data, superseded_id) VALUES (?, ?, ?, ?)', ['USER_EMAIL_UPDATED', 101, JSON.stringify({ email: 'alice.new@example.com' }), previousLog ? previousLog.id : null] ); console.log('User email update log entry:', updateLogResult.info.affectedRows); // Querying the full history for a user const history = await client.query('SELECT * FROM audit_log WHERE user_id = ? ORDER BY timestamp ASC', [101]); console.log('\nFull audit history for user 101:'); history.forEach(entry => console.log(entry)); } catch (err) { console.error('Database operation failed:', err); } finally { if (client.connected) { await client.end(); console.log('Connection closed.'); } } } runImmutableExample();