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Node.js - PostgreSQL Group rows by days

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Created by:
Dollie-Rutledge
416

In this article, we would like to show you howΒ in the group rows by daysΒ inΒ PostgresΒ database from Node.js level.

Node.js - PostgreSQL Group rows by days
Table used in the example - HeidiSQL

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

const pg = require('pg');

const types = pg.types;
types.setTypeParser(1114, (stringValue) => {
    return stringValue;
});

const client = new pg.Client({
    host: '127.0.0.1',
    user: 'my_username',
    database: 'my_database',
    password: 'my_password',
    port: 5432,
});

const fetchEventsGroupedByMonths = async () => {
	const query = `
            SELECT
                DATE_TRUNC('day', "event_timestamp") AS "day",
                COUNT(*)
            FROM "events"
            GROUP BY DATE_TRUNC('day', "event_timestamp")
            ORDER BY DATE_TRUNC('day', "event_timestamp")
    `;
    await client.connect();  // creates connection
    try {
        const { rows } = await client.query(query);  // sends query
        return rows;
    } finally {
        await client.end();  // closes connection
    }
};

fetchEventsGroupedByMonths()
    .then(result => console.table(result))
    .catch(error => console.error(error.stack));

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”€β”
β”‚ (index) β”‚          day          β”‚ count 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”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€
β”‚    0    β”‚ '2021-03-11 00:00:00' β”‚  '1'  β”‚
β”‚    1    β”‚ '2021-03-21 00:00:00' β”‚  '1'  β”‚
β”‚    2    β”‚ '2021-03-22 00:00:00' β”‚  '2'  β”‚
β”‚    3    β”‚ '2021-03-23 00:00:00' β”‚  '1'  β”‚
β”‚    4    β”‚ '2021-04-05 00:00:00' β”‚  '2'  β”‚
β”‚    5    β”‚ '2021-04-16 00:00:00' β”‚  '1'  β”‚
β”‚    6    β”‚ '2021-04-17 00:00:00' β”‚  '1'  β”‚
β”‚    7    β”‚ '2021-04-23 00:00:00' β”‚  '3'  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”€β”€β”˜

Database preparation

create_tables.sqlΒ file:

CREATE TABLE "events" (
	"id" SERIAL NOT NULL,
	"event_timestamp" TIMESTAMP NOT NULL,
	PRIMARY KEY ("id")
);

insert_data.sqlΒ file:

INSERT INTO "events" 
    ("event_timestamp")
VALUES
    ('2021-03-11 11:41:31'),
    ('2021-03-21 12:42:32'),
    ('2021-03-22 14:44:34'),
    ('2021-03-22 15:45:35'),
    ('2021-03-23 16:46:36'),
    ('2021-04-05 17:47:37'),
    ('2021-04-05 19:49:39'),
    ('2021-04-16 20:50:40'),
    ('2021-04-17 15:45:35'),
    ('2021-04-23 16:46:36'),
    ('2021-04-23 19:49:39'),
    ('2021-04-23 20:50:40');

Native SQL query (used in the above example):

SELECT
    DATE_TRUNC('day', "event_timestamp") AS "day",
    COUNT(*)
FROM "events"
GROUP BY DATE_TRUNC('day', "event_timestamp")
ORDER BY DATE_TRUNC('day', "event_timestamp")

Node.js - PostgreSQL - dates

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