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Node.js - PostgreSQL GROUP BY

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Created by:
Selina-Miranda
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In this article, we would like to show you how to use PostgreSQLΒ GROUP BYΒ in Node.js.

Example data used with GROUP BY statement - HeidiSQL
Example data used with GROUP BY statement - HeidiSQL

Note:Β 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 fetchGroupedUsers = async () => {
    const query = `SELECT COUNT("id") AS "number of users", "country"
                   FROM "users"
                   GROUP BY "country"
                   ORDER BY COUNT("id") DESC;`;
    try {
        await client.connect();                     // creates connection
        const { rows } = await client.query(query); // sends query
        console.table(rows);
    } catch (error) {
        console.error(error.stack);
    } finally {
        await client.end();                         // closes connection
    }
};

fetchGroupedUsers();

Result:Β 

β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
β”‚ (index) β”‚ number of users β”‚  country  β”‚
β”œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€
β”‚    0    β”‚       '3'       β”‚  'Spain'  β”‚
β”‚    1    β”‚       '2'       β”‚ 'Vietnam' β”‚
β”‚    2    β”‚       '1'       β”‚  'Italy'  β”‚
β”‚    3    β”‚       '1'       β”‚ 'Poland'  β”‚
β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜

Database preparation

create_tables.sqlΒ file:

CREATE TABLE "users" (
	"id" SERIAL,
	"name" VARCHAR(100) NOT NULL,
	"country" VARCHAR(15) NOT NULL,
	PRIMARY KEY ("id")
);

insert_data.sqlΒ file:

INSERT INTO "users"
	("name", "country")
VALUES
    ('Tom', 'Poland'),
    ('Chris', 'Spain'),
    ('Jack', 'Spain'),
    ('Kim', 'Vietnam'),
    ('Marco', 'Italy'),
    ('Kate', 'Spain'),
    ('Nam', 'Vietnam');

Node.js - PostgreSQL

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