We will start with creating a simple node application with a basic structure and then connecting with local sql server database and performing some queries on that database.

Step 1: Create a directory/folder by the name of project which you intent to create. Initialize a node application using npm init command which will create a package.json in current directory .

mkdir mySqlApp
//folder created 
cd mwSqlApp
//change to newly created directory
npm init
//answer all the question ..
npm install
//This will complete quickly since we have not added any packages to our app.

Step 2: Now we will create a App.js file in this directory and install some packages which we are going to need to connect to sql db.

sudo gedit App.js
//This will create App.js file , you can use your fav. text editor :)
npm install --save mssql
//This will install the mssql package to you app

Step 3: Now we will add a basic configuration variable to our application which will be used by mssql module to establish a connection .

console.log("Hello world, This is an app to connect to sql server.");
var config = {
        "user": "myusername", //default is sa
        "password": "yourStrong(!)Password",
        "server": "localhost", // for local machine
        "database": "staging", // name of database
        "options": {
            "encrypt": true
        }
      }

sql.connect(config, err => { 
    if(err){
        throw err ;
    }
    console.log("Connection Successful !");

    new sql.Request().query('select 1 as number', (err, result) => {
        //handle err
        console.dir(result)
        // This example uses callbacks strategy for getting results.
    })
        
});

sql.on('error', err => {
    // ... error handler 
    console.log("Sql database connection error " ,err);
})

Step 4: This is the easiest step ,where we start the application and the application will connect to the sql server and print out some simple results .

node App.js
// Output : 
// Hello world, This is an app to connect to sql server.
// Connection Successful !
// 1

To use promises or async for query execution refer the official documents of the mssql package :

• Promises
• Async/Await