SQL Server database integration

1. Install Required Packages: If you haven’t already, install the required npm packages for SQL Server and Node.js by running the following command:

  
    npm install express mssql
  

2. Create an Express App with SQL Server Integration: Create a file (e.g., app.js) and set up your Express app with SQL Server integration:

  
// Import required modules
const express = require('express');
const sql = require('mssql');

// Create an Express application
const app = express();
const port = 3000;

// SQL Server connection configuration (replace with your actual connection details)
const config = {
    user: 'your-username',
    password: 'your-password',
    server: 'your-server',
    database: 'your-database',
    options: {
        encrypt: true, // Use this option if you're on Windows Azure
    },
};

// Connect to SQL Server
sql.connect(config, (err) => {
    if (err) {
        console.error('Error connecting to SQL Server:', err);
        return;
    }

    console.log('Connected to SQL Server');

    // Define a route for retrieving data from the database
    app.get('/data', async (req, res) => {
        try {
            // Execute a simple SQL query to retrieve data
            const result = await sql.query('SELECT * FROM YourTable');
            res.json(result.recordset);
        } catch (error) {
            console.error('Error retrieving data from SQL Server:', error);
            res.status(500).send('Internal Server Error');
        }
    });

    // Start the server
    app.listen(port, () => {
        console.log(`Server running at http://localhost:${port}/`);
    });
});
  

3. Run Your Express App: In the terminal, run the following command to start your Express app:

     
       node app.js
     
   

   The server will start and connect to the SQL Server database.
4. Access Your Express App: Open your web browser and navigate to http://localhost:3000/data to retrieve data from the SQL Server database. Note that you’ll need to replace 'YourTable', 'your-username', 'your-password', 'your-server', and 'your-database' with your actual table name, SQL Server login credentials, server details, and database name.
5. This example demonstrates connecting to a SQL Server database using the mssql library, executing a simple query to retrieve data, and defining a route to expose that data through an Express endpoint.

MongoDB database integration

In this example, we’ll use the popular MongoDB database and the mongodb Node.js driver to demonstrate how to connect to a MongoDB database, perform CRUD (Create, Read, Update, Delete) operations, and interact with data.

1. 1. Install Required Packages: If you haven’t already, install the required npm packages for MongoDB and Node.js by running the following commands:

    npm install express mongodb
  

1. 1. Create an Express App with MongoDB Integration: Create a file (e.g., app.js) and set up your Express app with MongoDB integration:

    // Import required modules
    const express = require('express');
    const { MongoClient } = require('mongodb');
    
    // Create an Express application
    const app = express();
    const port = 3000;
    
    // MongoDB connection string (replace with your actual MongoDB connection string)
    const mongoURI = 'mongodb://localhost:27017/your-database-name';
    
    // Connect to MongoDB
    MongoClient.connect(mongoURI, { useNewUrlParser: true, useUnifiedTopology: true }, (err, client) => {
        if (err) {
            console.error('Error connecting to MongoDB:', err);
            return;
        }
    
        console.log('Connected to MongoDB');
    
        // Create a MongoDB collection (replace 'exampleCollection' with your desired collection name)
        const collection = client.db().collection('exampleCollection');
    
        // Define a route for retrieving data from the database
        app.get('/data', async (req, res) => {
            try {
                // Retrieve data from the collection
                const data = await collection.find().toArray();
                res.json(data);
            } catch (error) {
                console.error('Error retrieving data from MongoDB:', error);
                res.status(500).send('Internal Server Error');
            }
        });
    
        // Start the server
        app.listen(port, () => {
            console.log(`Server running at http://localhost:${port}/`);
        });
    });
    
  

1. Run Your Express App: In the terminal, run the following command to start your Express app:

   
       node app.js
     

   The server will start and connect to the MongoDB database.

2. Access Your Express App: Open your web browser and navigate to http://localhost:3000/data to retrieve data from the MongoDB collection. Note that you’ll need to replace 'exampleCollection' and 'your-database-name' with your actual collection name and database name.

This example demonstrates connecting to a MongoDB database using the mongodb driver, creating a collection, and defining a route to retrieve data from the collection. Feel free to expand on this example by adding routes for inserting, updating, or deleting data, based on your application’s requirements.