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Node.js - PostgreSQL - GROUP BY multiple columns

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Created by:
Dirask Admin - MR
1340

In this article, we would like to show you how to GROUP BY multiple columns in the PostgreSQL database using Node.js.

Node.js - PostgreSQL - GROUP BY multiple columns
Data used in the example - HeidiSQL

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 fetchUsers = async () => {
	const query = `SELECT "name", "department_id", COUNT(*)
				   FROM "users"
				   GROUP BY "name","department_id"
				   ORDER BY "name";`;
    try {
        await client.connect(); // gets connection
        const { rows } = await client.query(query); // sends query
        console.table(rows);
    } catch (error) {
        console.error(error.stack);
    } finally {
        await client.end();     // closes connection
    }
};

fetchUsers(); 

Result: 

┌─────────┬─────────────┬───────────────┬───────┐
│ (index) │    name     │ department_id │ count │
├─────────┼─────────────┼───────────────┼───────┤
│    0    │  'Ailisa'   │       3       │  '2'  │
│    1    │   'Chris'   │       3       │  '2'  │
│    2    │ 'Gwendolyn' │       2       │  '1'  │
│    3    │   'John'    │       1       │  '1'  │
│    4    │   'Kate'    │       3       │  '2'  │
│    5    │   'Simon'   │       3       │  '2'  │
│    6    │   'Simon'   │       2       │  '1'  │
└─────────┴─────────────┴───────────────┴───────┘

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, '2000.00'),
	('Chris', 'Brown', 3, '2000.00'),
	('Chris', 'Lewis', 3, '2000.00'),
	('Kate', 'Lewis', 3, '2000.00'),
	('Kate', 'Stewart', 3, '2000.00'),
	('Ailisa', 'Lewis', 3, '2000.00'),
	('Ailisa', 'Gomez', 3, '3000.00'),
	('Gwendolyn', 'James', 2, '3000.00'),
	('Simon', 'James', 2, '2000.00'),
	('Simon', 'Brown', 3, '2000.00'),
	('Simon', 'Collins', 3, '3000.00');

Native SQL query (used in the above example):

SELECT "name", "department_id", COUNT(*)
FROM "users"
GROUP BY "name","department_id"
ORDER BY "name"

Node.js - PostgreSQL

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