PostgreSQL - GROUP BY statement

In this article, we would like to show you how to use GROUP BY statement in PostgreSQL.

Quick solution:

SELECT "column1", "column2", "columnN"
FROM "table_name"
WHERE condition
GROUP BY "column_name"
ORDER BY "column_name";

Practical example

To show how the GROUP BY statement works, we will use the following table:

Note:

At the end of this article you can find database preparation SQL queries.

Example

In this example, we will display the number of users in each country descending.

Query:

SELECT COUNT("name") AS "number of users", "country"
FROM "users"
GROUP BY "country"
ORDER BY COUNT("name") DESC;

Output:

Database preparation

create_tables.sql file:

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

insert_data.sql file:

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