Example 11 + Instructions

Code-examples/Ex11/Instructions-for-db.md

+In order to test the server-to-server data transfer and the database query optimization, you need to have a MySQL database set up with some data in it. Here's a step-by-step guide on how you could set up a simple MySQL database for testing:
+
+1. **Install MySQL**: If you don't have MySQL installed, you'll need to install it. You can download it from the [official MySQL website](https://dev.mysql.com/downloads/) or use a package manager for your operating system.
+
+2. **Set Up the Database**:
+   - Log in to the MySQL server using a command-line client or a GUI tool like MySQL Workbench.
+   - Create a new database:
+
+   ```sql
+   CREATE DATABASE my_project_db;
+   ```
+
+   - Select the database:
+
+   ```sql
+   USE my_project_db;
+   ```
+
+   - Create a `users` table:
+
+   ```sql
+   CREATE TABLE users (
+     id INT AUTO_INCREMENT PRIMARY KEY,
+     name VARCHAR(255) NOT NULL,
+     address VARCHAR(255) NOT NULL,
+     email VARCHAR(255),
+     phone VARCHAR(255),
+     -- Add any other columns you might want
+     created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+   );
+   ```
+
+   - Insert some sample data into the `users` table:
+
+   ```sql
+   INSERT INTO users (name, address, email, phone) VALUES
+   ('Alice', '123 Main St', 'alice@example.com', '555-1234'),
+   ('Bob', '456 Maple Ave', 'bob@example.com', '555-5678'),
+   ('Charlie', '789 Oak St', 'charlie@example.com', '555-9012');
+   ```
+
+3. **Configure Your Node.js Application**:
+   - Update the MySQL connection pool configuration in your `server.js` file with the correct database credentials and the name of the database you just created (`my_project_db`).
+
+4. **Run Your Node.js Server**:
+   - Execute `node server.js` to start your server.
+
+5. **Test the Endpoint**:
+   - Use a web browser, `curl`, or a tool like Postman to make a request to `http://localhost:3000/user/1`.
+   - You should receive a JSON response with the name and address of the user with ID 1.
+
+This setup will allow you to test the optimized database query and ensure that your application server is only fetching the necessary data from the MySQL database, thus minimizing server-to-server data transfer.
\ No newline at end of file

Code-examples/Ex11/Instructions.md

+For this example, let's assume we have a Node.js application server that communicates with a MySQL database.
+
+**Backend Setup:**
+
+1. **Install Node.js**: If you haven't already, install Node.js from [nodejs.org](https://nodejs.org/).
+
+2. **Set up your project directory**:
+
+```bash
+mkdir my_project
+cd my_project
+npm init -y
+```
+
+3. **Install necessary packages** (Express for the server and a MySQL client for database interaction):
+
+```bash
+npm install express mysql2
+```
+
+4. **Create a file named `server.js`** and add the following code:
+
+```javascript
+const express = require('express');
+const mysql = require('mysql2');
+
+const app = express();
+const port = 3000;
+
+// Create a MySQL connection pool (adjust credentials as needed)
+const pool = mysql.createPool({
+  host: 'your_database_host',
+  user: 'your_database_user',
+  password: 'your_database_password',
+  database: 'your_database_name',
+  waitForConnections: true,
+  connectionLimit: 10,
+  queueLimit: 0
+});
+
+// Endpoint to get user's name and address by ID
+app.get('/user/:id', (req, res) => {
+  const userId = req.params.id;
+
+  // Optimized query to fetch only the necessary columns
+  pool.query('SELECT name, address FROM users WHERE id = ?', [userId], (error, results) => {
+    if (error) {
+      res.status(500).send('Error fetching user data');
+      return;
+    }
+    res.json(results[0]);
+  });
+});
+
+app.listen(port, () => {
+  console.log(`Server running on port ${port}`);
+});
+```
+
+Replace `'your_database_host'`, `'your_database_user'`, `'your_database_password'`, and `'your_database_name'` with your actual MySQL database credentials.
+
+**Testing the Setup:**
+
+1. **Run the server**:
+
+```bash
+node server.js
+```
+
+2. **Test the endpoint**:
+
+You can test the endpoint using a tool like `curl` or Postman, or simply by visiting `http://localhost:3000/user/1` in your web browser (assuming there is a user with ID 1).
+
+With `curl`, the command would look like this:
+
+```bash
+curl http://localhost:3000/user/1
+```
+
+You should receive a JSON response with only the name and address of the user, demonstrating that the server is only transferring the necessary data from the database.
\ No newline at end of file

Code-examples/Ex11/package.json

+{
+  "name": "ex11",
+  "version": "1.0.0",
+  "description": "",
+  "main": "server.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "start": "node server.js"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC"
+}

Code-examples/Ex11/server.js

+const express = require('express');
+const mysql = require('mysql2');
+
+const app = express();
+const port = 3000;
+
+// Create a MySQL connection pool (adjust credentials as needed)
+const pool = mysql.createPool({
+  host: 'your_database_host',
+  user: 'your_database_user',
+  password: 'your_database_password',
+  database: 'your_database_name',
+  waitForConnections: true,
+  connectionLimit: 10,
+  queueLimit: 0
+});
+
+// Endpoint to get user's name and address by ID
+app.get('/user/:id', (req, res) => {
+  const userId = req.params.id;
+
+  // Optimized query to fetch only the necessary columns
+  pool.query('SELECT name, address FROM users WHERE id = ?', [userId], (error, results) => {
+    if (error) {
+      res.status(500).send('Error fetching user data');
+      return;
+    }
+    res.json(results[0]);
+  });
+});
+
+app.listen(port, () => {
+  console.log(`Server running on port ${port}`);
+});