PostgreSQL - WHERE clause

In this article, we would like to show you how to use WHERE clause in PostgreSQL.

Quick solution:

SELECT "column1", "column2", ...
FROM "table_name"
WHERE condition;

Practical example

To show how the WHERE clause works, we will use the following table:

Note:

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

Example 1

In this example, we will display information about every user whose salary is greater than 3000.

Query:

SELECT * FROM "users" WHERE "salary" > 3000;

Output:

Example 2

In this example, we will display information about every user whose name is John.

Query:

SELECT * FROM "users" WHERE "name" = 'John';

Output:

Note:

PostgreSQL requires single quotes ('') around text values.

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');