Node.js - PostgreSQL COUNT()

In this article, we would like to show you how to use SQL COUNT() function in Node.js.

Note: at the end of this article you can find database preparation SQL queries.

const { Client } = require('pg');

const client = new Client({
    host: '127.0.0.1',
    user: 'postgres',
    database: 'database_name',
    password: 'password',
    port: 5432,
});

const countAllUsers = async () => {
    const query = `SELECT COUNT(*) AS "number of users" FROM "users"`;
    try {
        await client.connect();                      // gets connection
        const { rows } = await client.query(query);  // sends queries
        console.log(rows);
    } catch (error) {
        console.error(error.stack);
    } finally {
        await client.end();                          // closes connection
    }
};

countAllUsers();

Output: 

[ { 'number of users': 8 } ]

Database preparation

create_tables.sql file:

CREATE TABLE "users" (
	"id" SERIAL,
	"name" VARCHAR(50) NOT NULL,
	"surname" VARCHAR(50) NOT NULL,
	"department_id" INTEGER,
    "salary" DECIMAL(15,2) NOT NULL,
	PRIMARY KEY ("id")
);

insert_data.sql file:

INSERT INTO "users"
	( "name", "surname", "department_id", "salary")
VALUES
	('John', 'Stewart', 1, '3512.00'),
	('Chris', 'Brown', 2, '1344.00'),
	('Kate', 'Lewis', 3, '6574.00'),
	('Ailisa', 'Gomez', NULL, '6500.00'),
	('Gwendolyn', 'James', 2, '4200.00'),
	('Simon', 'Collins', 4, '3320.00'),
	('Taylor', 'Martin', 2, '1500.00'),
	('Andrew', 'Thompson', NULL, '2100.00');