In this tutorial, we will learn how to "Connect Postgresql database with Nodejs".

Prerequisite

Before we get started, make sure all these technologies are installed on your local machine.

1. Nodejs v+ 18 already installed,

2. PostgreSQL Driver already installed;

Sample Project

In our sample project, we will build a simple database store that has the names of employees and salary range;

Create a new database collection

1. Create a new database

    CREATE DATABASE organisation;
   

2. Check if the database is created

    \l
   

3. Connect to the database

    \c organisation;
   

4. Create a data collection of employee

    CREATE TABLE employee (
        emp_id     INT PRIMARY KEY,
        first_name VARCHAR(50) NOT NULL,
        last_name VARCHAR(50) NOT NULL,
        gender CHAR(1),
        birthdate DATE,
        email VARCHAR(100) UNIQUE,
        salary INT
    );
   

5. To check whether the employee table is created.

    \d employee;
   

Insert Table

Insert table is used for adding rows of data into the database. Now let's insert the data into your database, if you check your table using \d employee you would notice that the row and column of the table are empty.

INSERT INTO employee(emp_id, first_name, last_name, gender, birthdate, email, salary)
VALUES(1,'Annie','Smith','M', DATE '1988-01-09', 'emma@email.com',5000);

SELECT

SELECT will list all the data available in the employee table.

SELECT * FROM employee;

Create Our Nodejs App

Let's connect our Nodejs app to our PostgreSQL database. For more find the GitHub repository here: https://github.com/EmmaUmeh/NodePostgresql

1. Initialize your Nodejs project

    npm init --y
   

2. Install PostgreSQL database dependency

    npm install pg
   

3. Create a databasepostgres.js file

    const {Client} = require('pg');
   
    const client = new Client({
       host: "localhost",
        user: "postgres", //default PostgreSQL username
        port: 5432, //default PostgreSQL port number
        password: "*****", //default PostgreSQL password
        database: "postgres" 
    })
   
    client.connect(); //connect() connects our database
   
    client.query('SELECT * FROM employee', (err, res) => {
   
        return(!err) ? console.log(res.rows) : console.log(err.message);
   
    })
   

4. Now let's run this to check whether it is connected.

    node databasepostgres
   

5. In the terminal console, you would see the database running.

   

Conclusion

Furthermore, we have connected a simple database store using nodejs, what other technologies would you like to use in the future for your project, Let's us know in our comment section.