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PostgreSQL - AVG() function example

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Created by:
Nabila-Burnett
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In this article, we would like to show you how to use AVG() function in PostgreSQL.

Quick solution:

SELECT AVG("column_name") FROM "table_name";

Practical example

To show how the AVG() function works, we will use the following table:

PostgreSQL - example data used with AVG() function
PostgreSQL - example data used with AVG() function

Note:

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

Example 1

In this example, we will display the average salary.

Query:

SELECT AVG("salary") FROM "users";

Output:

PostgreSQL - AVG() function result
PostgreSQL - AVG() function result

Example 2

In this example, we will display every user whose salary is less than average. This shows that we are able to use AVG() function in different places in query (e.g. as subselect or having).

Query:

SELECT * FROM "users" 
WHERE "salary" < (SELECT AVG("salary") 
FROM "users");

Output:

PostgreSQL - AVG() function inside subselect (HeidiSQL)
PostgreSQL - AVG() function inside subselect (HeidiSQL)

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');

PostgreSQL - Functions

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